Kosher or coarse salt and freshly ground pepper to taste
Soak about 20 6-inch wooden skewers, or 10 12-inch skewers, in water to cover for 30 minutes. You can also use metal skewers, which do not need soaking.
Combine the lemon or lime juice, garlic, olive oil, herbs of choice, salt and pepper in a small bowl or plastic container and mix well.
Place the vegetables in a mixing bowl, then pour oven the marinade and toss to combine. Marinate for 30 minutes at room temperature, or refrigerate, covered, for at least 2 hours and up to a day.
Thread the skewers with the veggies, creating appealing patterns. Lightly salt and pepper the skewers.
Heat the grill to medium-high. Grill the kebabs 4 inches from the heat sauce, until the vegetables are meat or seafood is cooked through and everything has a nice grill-marked exterior, anywhere from 8 to 15 minutes depending on which vegetable you choose. Brush the kebabs with some of the marinade left behind in the bowl as they grill.
Serve hot or at room temperature.
If you are looking to grill more dense vegetables, like potatoes, cauliflower, broccoli, winter squash, and the like, it is usually smart to par cook them before grilling them, meaning to cook them part way through. Because they are so hard they will take a very long time to become tender on the grill, and because of that you will find it a little too easy to char the outsides before the insides become soft. And, if you are cooking other vegetables or meat on a skewer with these denser vegetables those other items will cook through much more quickly, and you will end up with some overcooked items (dry chicken or mushy tomatoes) while you wait for the broccoli or squash to become tender.