¾ cup extra-virgin olive oil, plus more for greasing
⅓ cup red wine vinegar or sherry vinegar
2 tablespoons plus 2 teaspoons whole-grain mustard
finely chopped 1 large shallot
Kosher salt and black pepper, to taste
Grill zucchini, eggplant, green beans or snap peas for 2 pounds. Green peppers (bell, shishito, mini), broccoli rabe, broccolini, asparagus, radicchio, fennel, corn on the cob
Fill a gas grill for two-zone cooking with medium-high heat by laying the coals on one half of the grill. Turn one of the end burners off before grilling on a gas grill.
While the grill heats, prepare the marinade: In a medium mixing bowl, whisk 3/4 cup oil, vinegar, mustard, and shallot until well combined. Season with salt and pepper to taste. Cut the vegetables into pieces that will not slip through the grates, for tiny or thin veggies like snap peas or green beans, leave them whole.
Take the marinade, vegetables, and tongs to the grill when ready. Clean the grates with a grill brush before oiling them with a paper towel. Grilling time will vary depending on the density and size of the veggies: 2 to 15 minutes, depending on how browned and soft they get. (When using a gas barbecue, cook with the lid down to help the vegetables steam and char.)
As the veggies cook, add them to the marinade. Allow the vegetables to soak in the marinade for at least 5 minutes. The vegetables may be refrigerated for up to 3 days. Serve immediately after bringing it back to room temperature.