Make the rice: bring the stock or water to a boil over high heat. Stir in the rice, butter, and salt. Cover tightly and remove to the lowest possible heat. Cook for 20 minutes. Remove from the heat. Allow to sit for 5 minutes.

Meanwhile, in a large skillet, heat 2 tablespoons of olive oil. Saute the onion over medium-high heat until soft, about 5 minutes. Add the zucchini and continue to sauté until beginning to soften, about 3 minutes. Stir in the tomatoes, cumin, paprika, and chili powder. Sauté over medium heat, stirring occasionally, until the tomatoes have released their juices, about 7 minutes.

Fluff the rice with a fork and transfer to the pan with the tomato mixture. Stir to combine. Off the heat, add the lemon juice and cilantro. Taste for seasoning.

Make the slaw: combine all ingredients in a medium-mixing bowl. Toss until incorporated. Taste for seasoning and add more salt as necessary.

Make the fish: Arrange the catfish fillets in a shallow bowl or baking dish. Pour the buttermilk over the fish. Marinate for 10 minutes.

Coat a cast iron skillet with a generous layer of olive oil over high heat. Place the cornmeal on a plate and season with salt and pepper. Remove the catfish from the buttermilk and dredge it in the cornmeal on both sides, shaking off any excess. When the pan is smoking, add the catfish fillets. Fry on both sides until golden brown and very crisp, about 3 minutes per side. Remove to a plate lined with paper towels. When the catfish is cool enough to touch, cut each fillet into two pieces.

To serve, place two cups of rice on each plate and top with two pieces of catfish. Using a slotted spoon and leaving as much juice as possible in the mixing bowl, scoop about ¼ cup of slaw on top of the fish. Garnish with fresh chopped parsley and some additional sliced radishes. Enjoy immediately!