Indian Shrimp with Cauliflower

1 pound medium shrimp, peeled and deveined

2 teaspoons garam masala

Kosher salt and freshly ground pepper

2 tablespoons extra-virgin olive oil

1 onion, diced

3 cloves garlic, chopped

3 tablespoons tomato paste

1 cup chopped fresh cilantro, plus more for topping

2 small russet potatoes (about 8 ounces each), peeled and diced

1 small head cauliflower, cut into florets (about 4 cups)

2 cups frozen peas, thawed

2 pieces naan or other flatbread, warmed and cut into wedges