Start by preheating your grill or grill pan over medium-high heat.
In a large mixing bowl, toss zucchini, bell peppers, broccoli, and carrots with olive oil, salt, black pepper, crushed red pepper, and minced garlic until evenly coated.
Place the vegetables on the grill and cook for about 3-4 minutes each side until they are tender and have visible grill marks.
While the veggies are grilling, begin making the peanut sauce. In a medium-sized bowl, combine peanut butter, soy sauce, lime juice, brown sugar, and minced garlic. Whisk them together.
Gradually add warm water, 1 tablespoon at a time, and continue whisking until the sauce reaches your desired consistency.