Preheat the oven to 425 degrees F. If using a pizza stone, heat the stone in the preheated oven for 10 minutes. A baking sheet can be used instead of a stone.
Preheat a grill or grill pan to medium-high heat.
Brush both sides of the zucchini, red bell pepper and red onion with olive oil and season with salt.
Grill the vegetables until just tender and slightly charred, about 2 minutes per side for the zucchini and bell peppers, and 3 to 4 minutes per side for the onions. If using a grill pan, it may be necessary to cook the vegetables in two batches.
Cut the zucchini pieces in half or thirds, cut the bell peppers in strips and cut the root end off of each onion wedge.
Spread about 2 teaspoons peanut sauce on each naan. Divide the vegetables evenly between the naans. Sprinkle each with 1 ½ tablespoons mozzarella.
Lay 4 pizzas on a pizza peel or on a baking sheet (if not using a baking stone). If using a pizza peel, transfer the pizzas from the peel to the preheated stone. If using a baking sheet, place the baking sheet in the oven.
Bake until the cheese is melted and the naan is golden brown, 7 to 8 minutes. Repeat with the remaining 4 pizzas.
Garnish with cilantro. Serve.
In a medium bowl, whisk together the peanut butter, lime juice, soy sauce, agave nectar, rice vinegar and chili garlic sauce until smooth.