Thaw fish, if frozen. Rinse fish; pat dry with paper towels. Measure thickness of fish. In a bowl stir together lime juice, ancho chile pepper, and salt. Brush lime mixture evenly over both sides of fish fillets.
In an extra-large nonstick skillet heat 2 teaspoons of the oil over medium-high heat. Add fish; cook 4 to 6 minutes per 1/2-inch thickness or until fish flakes easily, turning once. Remove fish from skillet. Cover and keep warm.
In the same skillet heat the remaining 1 teaspoon oil. Add the next four ingredients (through garlic); cook about 2 minutes or until vegetables are heated and are just starting to soften, stirring occasionally. Remove from heat.
Divide corn mixture among serving plates. Top with fish and sprinkle with cilantro. If desired, serve with lime wedges and/or additional jalapeño slices.
Chile peppers contain oils that can irritate your skin and eyes. Wear plastic or rubber gloves when working with them.
Chop a few jarred, pickled jalapeños and skip the fresh.