Curry Leaf Popcorn Chicken

Ingredients

• Seeds from 4 green cardamom pods
• coriander seeds
• cumin seeds
• whole black peppercorns
• buttermilk
• fresh lime juice
• serrano chiles, coarsely chopped
• scallions, roots removed, coarsely chopped
• " piece fresh ginger, peeled, chopped
• garlic cloves
• curry leaves, preferably fresh, divided
• plus 1 tsp. kosher salt
• cayenne pepper, divided
• skinless, boneless chicken breasts, patted dry, cut into 1" pieces
• all-purpose flour
• baking powder
• baking soda
• Neutral oil
• green Thai chiles, seeded if desired
• A spice mill or mortar and pestle