Ingredients

• 1 medium onion, halved lengthwise, then thinly sliced lengthwise
• 2 tablespoons vegetable oil
• 1 tablespoon minced fresh jalapeño, including seeds
• 1 garlic clove, minced
• 1 teaspoon finely grated peeled fresh ginger
• 1 teaspoon ground cumin
• 1 teaspoon ground coriander
• 3/4 teaspoon salt
• 1/8 teaspoon turmeric (optional)
• 1 lb tomatoes (3 medium), cut into 1/2-inch pieces
• 1 lb large shrimp in shell (21 to 25 per lb), peeled and deveined
• 1/2 cup loosely packed fresh cilantro leaves, chopped if desired

Instructions

1. Cook onion in oil in a 12-inch heavy skillet over moderate heat, stirring occasionally, until golden, 6 to 8 minutes. Add jalapeño, garlic, and ginger and cook, stirring, until jalapeño is softened and garlic is golden, about 1 minute. Add cumin, coriander, salt, and turmeric (if using) and cook, stirring, until fragrant, about 1 minute. Add tomatoes and cook, stirring occasionally, until tomatoes break down and sauce is thickened, 3 to 5 minutes.
2. Add shrimp and cook, turning occasionally, until just cooked through, about 3 minutes. Remove skillet from heat and stir in half of cilantro. Serve sprinkled with remaining cilantro.