1. Roast the corn over an open flame or under a broiler until just browned. When cool, cut the kernels from the cob. Put in a medium bowl and set aside.
2. Place the tomatillos in a small saucepan and cover with water. Bring to a boil, lower the heat and simmer until soft, about 5 minutes. Drain and purée in a blender until smooth. Pour into the bowl containing the corn. Add the tomatoes, jalapeños, cucumber, onion, red pepper, cilantro, lime juice, salt and pepper. Set aside.
For the sea bass:
1. In a large skillet, heat the olive oil over medium heat.
2.Pour the buttermilk into a shallow dish and sprinkle the cornmeal onto another shallow dish. Season the fish fillets with salt and pepper; dip each fillet into buttermilk, then dredge in cornmeal.
3. Sauté the fish fillets until lightly browned, 3 to 4 minutes per side.
4. Transfer to warm plates and serve with room-temperature salsa on the side.