Preheat oven to 475°. In a large bowl, whisk together flour, 1/2 cup panko, the garam masala, baking soda, salt, and remaining spices. Whisk in lemon juice and club soda. Set aside.
In a small bowl, use a clean whisk to beat egg whites until foamy.
Whisk whites into flour mixture. Using your hands or a spatula, add cauliflower and combine until all florets are coated. Place remaining panko in a medium bowl. Lift florets, 1 at a time, out of batter and toss to coat with panko.
Place florets on a large nonstick baking sheet coated with oil. Bake until browned and crispy, about 20 minutes. While cauliflower bakes, make Cilantro Mint Dipping Sauce.
Note: Nutritional analysis is per serving without sauce.