Preheat oven to 375°.

Toss the onions with about ½ cup of the olive oil and about 1- ½ teaspoons salt (if using kosher salt, use a little more). Add the garlic, olives, and mint.

Trim off one pithy end of the lemon, then slice it as thin as possible into half-moons, stopping when you hit pith at the other end. Remove seeds as you encounter them. Toss the lemon slices with the onion mixture, add the white wine, and set aside to let the onions soften and “weep” their moisture while you trim the artichokes.

Trim the bottom of the stem of each artichoke and carefully peel the stalk. Remove badly damaged or dry outer leaves. Trim the thorns with scissors or slice them off with a sharp paring knife. Cut the artichoke in half, then use a stainless steel spoon to carve under and remove the thistley choke, leaving the meaty bottom intact. Rinse in cold water; don’t drain well—a little water between the leaves helps ensure that the artichokes cook thoroughly and evenly.

Sprinkle the artichokes with salt, squeezing and folding them so some salt falls between the leaves. Drizzle and rub with olive oil to coat thoroughly, then squeeze the halves so you can trickle and rub some oil between the leaves.

Spread the juicy onion mixture about 1- ½ inches deep in a large, flameproof baking dish (I use a 10- by 14-inch lasagna pan). The liquid should be about ½ inch deep; if not, add a little water. (This puddle will generate steam to keep the artichokes moist as they cook.) Nestle the artichokes cut side down in the bed of onions. They will be crowded.

Heat gently over a low flame until the puddle is bubbling, then cover tightly—first with parchment paper, then foil, dull side out—and bake until you can easily pull out a second-tier leaf and the pulp at its base is tender. This usually takes about 1-1 ½ hours; the exact size of the artichokes, as well as the baking dish and oven performance, will affect the cooking time. Be aware that the outermost layer of leaves will emerge a little leathery, which I like.

Once a test leaf is tender, raise the oven temperature to 400°, uncover, and bake for about 15 minutes longer to concentrate the flavors and lightly brown the tips of the vegetables. Serve hot, warm, or cold, as is, or with homemade mayonnaise flavored with lemon, garlic, or a few chopped anchovy fillets.

Cover any leftovers tightly and refrigerate; they will be silkier and sweeter the next day. Bring to room temperature before serving, or heat slowly, loosely covered, in a 300° oven.