Step 1

In a bowl, combine the lemon juice, serrano, garam masala, cayenne, turmeric, mustard powder and coriander. Add the shrimp and toss to coat.

Step 2

In a large nonstick skillet, heat the oil. Add the cumin seeds and cook over moderate heat, stirring, until deeply golden, 1 to 2 minutes. Add the shrimp, season with salt and cook, stirring occasionally, until curled and white throughout, about 2 minutes. Stir in the scallions and cilantro. Transfer the shrimp to plates and serve with lemon wedges.