I am in the middle of re-designing my sauce class. We do two pan sauces in that class (a red wine reduction for steak and a porcini sauce for chicken). Both are keepers. They are yummy and loaded with techniques that are easy, but not necessarily familiar to home cooks. We do a bechamel because it has many uses and is a good demo of how to work with a roux thickener. We do a vinaigrette because it's hard to live without it (unless you want to rely on store bought dressings and what fun would that be?!). The other two sauces I've been losing a lot of sleep over. Usually, it's a cilantro lime butter and a salsa verde (the Italian kind). While they are yummy and extremely versatile, I feel like I am not really teaching my students anything interesting with them. We are just executing recipes that any 10 year old is perfectly capable of following.
My criteria for choosing dishes we cook in class is their screw up potential. If not much can go wrong, I feel like it's a wasted opportunity. For this Saturday's sauce class, I am going to try something different. I'll try replacing cilantro lime butter and salsa verde with a pureed vegetable sauce to serve with our seafood dish.
Pureed vegetable sauces mostly appear in upscale restaurants that charge $25 and up per entree, but they are nothing more than good pureed vegetable soups served as sauces. In fact, I often do that at home when I have soup leftovers. Plop a piece of seared fish into some leftover asparagus soup and voila -- it's fine dining. Of course, these sauces are only as good as your soup making skills and there is a lot to learn when it comes to soups.
Instead of writing up a roasted red pepper sauce recipe, I'd like to write some general guidelines for creating vegetable puree sauces. This will free you up to improvise with whatever vegetables strike your fancy.
Choosing the vegetable
One way to choose a vegetable to use for sauce is to pay attention when you eat out. If you see a sauce you like, try recreating it at home. Another way is to check whether this kind of vegetable is commonly used for pureed soups (you can do that by googling). Here are some examples of vegetables that work well and produce beautifully smooth and rich purees:
- sweet peppers
- celery root
- butternut squash
- green peas
- swiss chard
At some point during this sauce making process your vegetable will be simmering in the flavorful liquid that you'll create, but some vegetables might benefit from being roasted first to enhance their flavor. I find that cauliflower and butternut squash come out very nicely when roasted first. Red peppers are great charred under an open flame until black and then peeled. That's what I did for my red pepper sauce. The easiest way to char a pepper is to cut off the flesh around the seeds into 4 flat pieces and put them under the broiler skin side up until they are black. Move to a bowl, cover, and let them steam for 20 minutes of so. They'll get softer and easier to peel just by rubbing with your hands. Once they are peeled and cut into medium dice, they are ready for simmer. Green vegetables, like asparagus and peas don't benefit from roasting and should be added to the simmering liquid raw to preserve their green color.
Start with the onion family
Like all vegetable soups, vegetable sauces need an onion to give them that wonderful sweet savory balance. My favorite onions to use are shallots. Leeks are also very nice paired with green vegetables. If you don't have either on hand, just use plain old yellow onions. Any onion is better than none. For 1 Lb of vegetable, you'll need roughly 1/4 to 1/3 cup of finely diced shallot (or leek or onion) sweated in 1-2 Tbsp olive oil or butter. Sweating means that you cook the onion on very low heat stirring often until it's completely soft and translucent, but develops no color. At this point, you are ready to add your main vegetable and liquid.
What liquids to use and how much
First let's get out of the way what not to use. Don't use boxed stocks. They make mediocre soups and sauces. Believe it or not, water works extremely well. If you happen to have some home-made vegetable or blond chicken stock (made from raw, not roasted chicken), you can use it in any vegetable sauce. If you have some brown chicken stock (made from roasted chicken), you can use it with anything but green vegetables. You'll also need a splash of dry white wine (use a ratio of about 5 parts stock to 1 part wine). This will give your sauce the necessary acidity. But if no wine is on hand, you can adjust acidity in the end by adding lemon juice to taste. When cooking green vegetables, I like to add some lemon juice to the cooking liquid to help preserve color.
Now the question of how much total liquid to use. I find that it works best when the liquid just barely comes to the top of the vegetables. Keep in mind that it's always easier to thin out the sauce in the end than to thicken it, so don't get carried away with liquid.
Don't forget the salt. Season, taste, and adjust.
Here is where you can let your imagination take over. Any sauce can benefit from a bay leaf and a few sprigs of thyme that you'll fish out before pureeing. There are also aromatics that pair particularly well with certain vegetables:
- asparagus and lemon zest
- salsify and orange zest
- sweet peppers and smoked paprika
- cauliflower and truffles (though it's best to add the truffle oil in the end rather than add it to the cooking liquid)
- celery root and vanilla bean (don's use the extract)
- carrots and ginger and/or oranges
Once your pot is assembled, simmer it gently until the vegetables are tender. Err on the overcooking side for root vegetables. Err on the undercooking side for green vegetables. But even those should not be crisp. They are lovely crisp when served as a side dish, but not in a soup or sauce. This can take as short as 5 minutes for green vegetables or as long as 25 minutes for root vegetables (maybe even longer if you chopped them rather large). Check the green ones often.
Pureeing, Straining, and Thickness Troubleshooting
You'll need a blender. An immersion type is my favorite since it makes the clean up easy. As tempting as it is to leave your sauce in the pot when using an immersion blender, I find that I get a smoother puree if I move it to a 2 cup pyrex measuring cup of some other tall container that fits the immersion blender snugly. Start on low speed until all the chunks are gone. Then puree on high speed for about 3 minutes unless your sauce is silky smooth before that. This might seem really long, but it will result in a much smoother sauce. Take a look at what you've got. It should look thicker than the sauce you were hoping to get because the straining process will thin it out.
If you are wondering if it might be smooth enough, stop wondering, and start straining. The texture difference between home-made soups and restaurant soups often just boils down to straining.
Set a fine mesh strainer over a bowl and pour the sauce into it. When using a fibrous vegetable (like asparagus, particularly white asparagus), it's helpful to let it sit in the strainer undisturbed for 5 minutes to shed excess liquid since it will be a lot thinner after straining. Pour the liquid that accumulates after 5 minutes into another bowl and reserve it for thinning out the sauce if necessary. Then force the sauce through a strainer by rubbing it with the back of the ladle in circular motion. Discard the fibers that didn't get through the sieve. Rinse out the sauce pot and return the strained sauce to it. If too thick to your liking, you can thin it out with reserved cooking liquid or more stock/water.
I know -- this does sound like a lot of work, but the good news is that you can make your sauce up to this stage a day in advance. Cool, cover, and refrigerate until ready to use. The only thing you'll have to do last minute is warm it up and enrich it with a little butter or cream.
When ready to serve, return the sauce to a gentle simmer. To enrich with cream, whisk it in and wait for the sauce to return to a simmer for about a minute. Make sure to use heavy cream (also sold as "heavy whipping cream," not half and half or light cream. But you are welcome to use as much or as little as you'd like. To enrich with butter, first take the sauce off heat. Then whisk in 1-2 Tbsp of butter per pound of vegetables. Since I only serve 1/4 - 1/3 cup of sauce per person, I make my sauces a lot richer than my soups.
Don't even think about pouring this sauce onto someone's plate without tasting it first. It might need more salt or a squirt of lemon. Taste and adjust until you are happy with it.
Phew -- you are done!
As far as protein/sauce pairing goes... Most of my vegetable sauces end up with seared and pan roasted seafood because making a pan sauce with the fond left over from searing seafood doesn't work (too fishy).