How to Grill Vegetables Without Them Falling Apart

The first and biggest factor is slice thickness. A thinly cut zucchini or eggplant becomes completely soft inside before the surface browns, and it splits in two as soon as the tongs touch it. A thick slice, by contrast, browns on the outside while keeping a firm core that holds it together. A practical guide is to cut slices about as thick as a finger; thinner slices are better suited to a skillet than a grill. The same thickness rule applies to the length of the pieces: short pieces fall easily through the grates.

The second factor is timing. As soon as a vegetable goes on the grill, its surface is moist and sticks to the grate; if you try to turn it at this stage, it stays on the grate and tears. Once a crust forms on the surface, the vegetable releases on its own and lifts with a single motion. For this reason, leave vegetables on the grill without moving them for a few minutes. Turning too soon can break apart even the thickest slice. Test whether a vegetable releases by sliding a thin spatula underneath it first, rather than lifting it with tongs. For the same reason, space the vegetables apart on the grill; pieces touching each other will lift together when turned.

The third factor is how the pieces are threaded on the skewers. Pieces threaded on a single skewer rotate around it when turned; the vegetable stays in place on the skewer, its side facing the heat does not change, and pieces that are forced may tear around the hole. When you thread the pieces onto two parallel skewers, they cannot rotate, and you can turn the whole skewer like a single flat surface. The difference is most noticeable with slippery vegetables such as tomatoes, mushrooms, and onions. If using wooden skewers, soak them in water beforehand; otherwise, they may catch fire and break over the heat.

Small pieces have a separate solution. Peas, corn kernels, small mushrooms, and chopped peppers fall through the grill grates; use a perforated grill basket or tray for these. Preheat the basket and spread the vegetables in a single layer. If you crowd the basket, the vegetables cook in their own steam instead of browning, and they still fall apart. Empty the basket as soon as you take it off the grill, because vegetables left on the hot metal continue to cook.

A prep step makes firm vegetables easier to grill. Potatoes, carrots, and pumpkin may become too dark on the outside before they soften on the grill; if you briefly boil them first and let them cool, they only need time on the grill to develop color. Move large, thick pieces away from directly over the coals to a cooler area of the grill; they can cook through there without burning on the outside. Always dry parboiled vegetables before putting them on the grill; a wet surface will not brown and will stick to the grate. To create a cooler area, pile the coals on one side of the grill and leave the other side empty.