1. Preheat oven to 200°F. Sprinkle the fillets with salt and pepper. Put the sesame seeds on a plate and dredge the fillets on both sides, pressing the seeds gently into the fish.
2. Heat 2 tsp each sesame and vegetable oils in a large nonstick skillet over medium-high heat and add 2 fillets.
3. Adjust the heat so the fish sizzles but doesn't burn. Cook until seeds on the bottom are toasted and top begins to turn opaque (2-3 minutes). Then carefully turn the fillets to cook on the other side (1-2 minutes).
4. Transfer to an ovenproof plate and keep warm in the oven. Repeat with remaining fillets. To serve, garnish with mint; serve with lime wedges.