Chilli–Lime Swordfish Steaks

I got the germ of this dish from Madhur Jaffrey’s Masala Fish Steak recipe, where she uses sweet red peppers as the base of the sauce. But I found her sauce too bland and better suited as a topping for grilled fish. So I amped-up the spice quotient with turmeric, coriander and black mustard, added fresh green chillies for heat, and cilantro and lime for freshness. I used swordfish here, but you can substitute with any firm-fleshed fish like salmon, trout, or cod.

Ingredients 

2 lbs [1 kg] Swordfish steaks
3 tbsp Turmeric
Salt, to taste
1 large Red Pepper, seeded, de-veined, and roughly chopped
2 Shallots, roughly chopped
6–8 cloves Garlic, peeled
2-inch piece Ginger, peeled and roughly chopped
4–6 fresh Green Chillies
¼ cup Cilantro
Grated zest of ½ Lime
4 tbsp Vegetable Oil
1½ tsp Black Mustard Seeds
1 tbsp ground Coriander
¼ tsp Black Pepper
Juice of ½ Lime

1. Rub fish steaks with turmeric and salt and set aside for at least 30 mins, and up to 4 hours. 
2. Put red peppers and shallots in a food processor and pulse 4–5 times. Add garlic, ginger, green chillies, cilantro and lime zest, and grind until the mixture is a smooth paste. Pour mixture into a bowl and set aside. 
3. Heat 2 tbsp oil in a large skillet or frying pan over high heat. Add fish and brown well on both sides. Remove fish and set aside on a platter. Discard oil in pan and wipe clean. 
4. Heat remaining oil in same pan over high heat. When the oil is smoking, add black mustard seeds and let sputter for a few seconds until they start to pop. Add red pepper mixture, stir and fry for about 3 mins. Turn heat to low, add coriander, black pepper and salt and continue frying for 2 mins, until the sauce starts to dry out. 
5. Transfer browned fish to the pan, add limejuice, and spoon sauce over the fish. If the pan is too dry, add 2–3 tbsp water. Put a lid on the pan and let simmer for about 2–3 mins, until the fish is cooked-through. Serve garnished with cilantro and lime wedges.