Lay bell peppers, zucchini, eggplant, and onion on baking sheets. Brush both sides of vegetables with Moroccan marinade (reserve any remaining).
Lay vegetables on a well-oiled grill over a solid bed of medium-hot coals or medium-high heat on a gas grill (you can hold your hand 1 to 2 in. above grill level only 3 to 4 seconds); close lid on gas grill. Cook vegetables, turning once, until beginning to brown and just tender when pierced, 7 to 8 minutes for eggplant, 8 to 10 for onion and bell peppers, and 12 for zucchini. Transfer to a large cutting board as done.
Cut vegetables into 1-in. pieces and put in a bowl. Add pine nuts, mint, and any remaining marinade. Mix, adding more vinegar, salt, and pepper to taste.