In a medium saucepan, heat 1 Tbsp. oil over medium heat until hot. Add garlic and stir until fragrant, about 30 seconds. Add the Black-Eyed peas and water or broth and bring to a boil. Reduce the heat to low and simmer uncovered about 35 - 40 minutes, until peas are tender. Meanwhile, in a large tall-walled frying pan or soup pot, heat the cooking oil for frying over high heat until 350 degrees. If you don't have a thermometer, when the oil appears to "shimmer,” throw a tiny pinch of flour in it. If it sizzles instantly and bubbles, the oil is hot enough. Pour the buttermilk onto a large plate, and the flour onto a second plate. Season each fish fillet with a pinch of salt & pepper. Dip each into the buttermilk, coating each side. Hold above the plate and allow all excess to drip off. Dredge in the flour evenly and shake off any excess. Carefully place in the hot oil and fry until golden brown and firm, about 5 - 6 minutes. Remove to a wire rack or paper towel lined tray when finished. When the peas are cooked through, season with salt & pepper and serve alongside the catfish.