I love this method of cooking zucchini. It is the one I return to time and again—and the recipe I have been asked for more than any other over the years. It works as an accompaniment with almost any dish. Use another soft herb in place of the tarragon if you like—the zucchini will happily partner basil, mint, parsley, or chervil. In order to achieve the gentle unctuous flavor and texture that you are looking for, it is essential to cook the zucchini really slowly over the gentlest possible heat, without letting them brown.
Trim the zucchini and slice them into fine rounds, about 1/8 in [3 mm] thick.
Put a large heavy-based pan over medium heat and add the olive oil and butter. Once the butter has melted, add the zucchini and stir well to coat the slices in the melted butter and oil. Add the crushed garlic and a good pinch of salt.
Now turn the heat down to its lowest possible setting and put a lid on the pan. Cook 40 minutes, stirring every few minutes to ensure that the zucchini do not stick to the bottom of the pan or brown. As the zucchini cook they will soften and their flavor will deepen, taking on a lovely garlicky aroma. Eventually they will begin to disintegrate, becoming almost like a thick mushy jam.
At this point, remove from the heat and add the chopped tarragon, plenty of pepper, and a good pinch of salt. Stir well and serve. These zucchini are surprisingly good eaten cold as well—often I toss them through a salad of leaves and cooked lentils dressed with a little olive oil and wine vinegar.
Excerpted from Spring by Skye Gyngell by arrangement with Quadrille Publishing, distributed by Chronicle Books. Copyright © 2016 by Skye Gyngell.
"Vegetables are perishable, so we don't have any indication of what they looked like 500 years ago," says James Nienhuis, a professor in the Department of Horticulture at the University of Wisconsin.