More like a Chinese stir-fry than a Sri Lankan curry, this dish makes for quick, convenient finger food, and a perfect accompaniment for a cold beer.
Wash, clean, and shell shrimp or cut squid into 1-inch strips.
Heat the oil in a pan. Sauté the onions, garlic, ginger, and curry leaves until the onions are translucent. Add tomatoes and serrano chiles.
Add shrimp or squid, cayenne, dry red chiles, vinegar, and salt and stir-fry for 2 minutes. Remove from heat, put on a plate, and squeeze on lime juice before serving.