Golden Vegetable Tart with Fresh Basil

The onions do most of the work in this tart, so give them the time. Sweet onions have a lot of natural sugar, and when they cook low and slow in a dry-ish skillet, that sugar browns into something jammy and deep without any added sweetener. Stirring in the balsamic vinegar at the end gives them a little tang, and that tang is what keeps the tart from tasting flat once the vegetables go on top. Vidalia and other sweet onions are mild enough to eat raw, which is part of why they caramelize so softly. If you can only find a regular yellow onion, expect a sharper result and a little more time at the stove.

Tomatoes and zucchini are a classic pairing in the way the French and Italians have cooked them for generations, and this tart borrows that idea. A tart is an easy way to show off summer produce, since the vegetables sit on top and get a gentle roast rather than being buried in a casserole. Zucchini is about 95 percent water, so cooking the slices in the skillet first drives off some moisture and keeps the tart from going soggy. That step is worth doing even if it feels like one more pan to wash.

The crust is forgiving. Keep the water very cold, stop mixing as soon as the dough holds together, and do not knead it. Shaggy dough is fine. If the edges crack when you move it into the pan, press them back together with your fingers. The Dijon spread on the bottom is more than flavor: it acts as a bit of glue and a sharp counterpoint to the sweet onion.

To store leftovers, cover the tart loosely and keep it in the fridge for up to three days. It is good cold or at room temperature, and a few minutes in a warm oven will bring back the crust. Leftover wedges also make a fine lunch next to a bowl of greens. For a meal around it, a simple plate of Quick Skillet Ratatouille echoes the same vegetables, and a bright Watermelon and Radish Salad with Mint cuts through the richness of the cheese and crust. If you want something heartier, a warm Sweet Onion and Tomato Simmered Okra makes a nice side that plays off the same flavors.