The word coulis describes any sort of smooth purée that has been strained to eliminate seeds and bits of peel. A tomato coulis is perfectly smooth and can be used alone either hot or cold, or to flavor other sauces, such as aurore and choron, mayonnaises, and beurre blanc. Depending on the quality of the tomatoes, tomato coulis can be raw or cooked. When preparing tomato coulis, you need only seed the tomatoes to eliminate excess liquid; peeling is not necessary because the skins will be strained out anyway. Tomato coulis can be used as the starting point and emulsifier for a hot or cold vinaigrette or stirred into whipped cream or crème fraîche and served as a cold sauce; mustard whisked in at the end lends a discreet tang.
To prepare raw tomato coulis, cut the tomatoes in half crosswise, squeeze out the seeds, and chop the halves with a chef’s knife. It is best to chop the tomatoes by hand; if dealing with a large quantity, a food processor can be used, but work the mixture as little as possible or the blade will break up any remaining seeds, making the mixture bitter. Strain the mixture through a fine strainer or a food mill with the finest plate.
Raw tomato coulis contains a large proportion of water, which will tend to separate out as the coulis sits in storage or, worse, while the coulis sits on the plate. Excess water can be eliminated in several ways.
- Coarsely chop and salt the tomatoes, as for tomato concassée, and allow them to drain before straining them.
- Place the tomato coulis in a chinois suspended over a pot or bowl for 2 to 3 hours. Gently stir the mixture inside the chinois every 20 minutes or so.
- Transfer the coulis to a tall container and ladle off the water as it gradually floats to the top.
- Blend 0.5% xanthan gum and 1% Ultra-Sperse 3 into the coulis.
Even when excess water has been eliminated from a raw tomato coulis, the microscopic particles of pigment tend to separate from the surrounding liquid, a phenomenon called syneresis. In some situations this will probably not even be noticed, but in more formal settings, in which a coulis is spread over the bottom of a large plate, it can be unsightly. For this reason some chefs combine raw tomato coulis with an emulsifier such as reduced heavy cream, a very small amount of egg yolk, or an appropriate hydrocolloid thickener or emulsifier.
Rinse the tomatoes, cut them in half crosswise, and squeeze out the seeds. Chop them coarsely, skins and all, and stew them with olive oil or another fat until they are completely soft and release all their liquid. Strain the mixture and reduce the liquid that runs through the strainer until it is syrupy. Purée the solids by working them through a food mill or a drum sieve. Combine the purée with the reduced liquid.
Copyright © 2017 by James Peterson. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.