Wash and dry all produce. Thinly slice radishes. Tear cilantro leaves from stems; discard stems. Halve lime, then cut one half into wedges. Peel carrot. Using a vegetable peeler, shave carrot lengthwise into long ribbons, rotating as necessary. Discard carrot core once it becomes too thin to shave.

In a medium bowl, toss carrot, radishes, 1/4 tsp sugar, and juice of half a lime. Season with salt and pepper and set aside to pickle.

In another medium bowl, mix 1/4 cup flour (we sent more), cornstarch, and baking powder. Whisk in 6 TBSP water. (TIP: Use more or less water as needed. The batter should have a runny but slightly thick consistency, like paint.) Season with salt and pepper.

Pat tilapia dry with a paper towel, then cut into 6 evenly sized pieces. Season all over with salt, pepper, and blackening spice.

Heat a thin layer of oil in a large pan over medium-high heat (we used 2 TBSP; Use a nonstick pan if you have one). Once oil is very hot, dip a piece of tilapia in batter, coating all over and letting excess drip off. Add to pan, then repeat with remaining fish. Cook until crisp and golden brown, 3-4 minutes per side. Transfer to a paper-towel-lined plate. Season with salt and pepper.

While fish cooks, wrap tortillas in a damp paper towel and microwave on high until warm, about 30 seconds. (TIP: Alternatively, wrap tortillas in foil and warm in oven for 5 minutes at 400 degrees.) Spread tortillas with sour cream. Top with tilapia (breaking it up into pieces to fit), veggies, and cilantro. Serve with lime wedges for squeezing.