Wash and dry all produce. Slice corn kernels off cob; discard cob. Trim and quarter cucumber lengthwise, then thinly slice crosswise. Dice tomato. Zest and quarter lime (quarter both limes for 4 servings). Roughly chop cilantro leaves and stems.

Combine rice, 3/4 cup water (11/2 cups for 4 servings) and a pinch of salt in a small pot. Bring to a boil, then cover and reduce to a gentle simmer. Cook until rice is tender, 15-18 minutes. Turn off heat; keep covered until ready to serve.

Meanwhile, heat a drizzle of oil in a large pan over medium-high heat. Add corn kernels and cook, stirring occasionally, until golden brown and lightly charred in spots, 3-5 minutes. (TIP: If corn begins to pop, cover pan with a lid.) Turn off heat; transfer to a medium bowl. Wipe out pan.

Pat tilapia dry with paper towels; season all over with salt, pepper, and Southwest Spice. Heat a large drizzle of oil in pan used for corn over mediumhigh heat. Add tilapia and cook until browned and cooked through, 4-6 minutes per side.

Meanwhile, add tomatoes, half the cucumber (use all for 4 servings), and half the cilantro to bowl with corn; toss to combine. Add a squeeze of lime juice and season with salt and pepper. In a small bowl, combine sour cream and half the lime zest. Add water, 1 tsp at a time, until mixture reaches a drizzling consistency. Season with salt and pepper.

Fluff rice with a fork and stir in 1 TBSP butter (2 TBSP for 4 servings) and remaining lime zest. Season with salt and pepper. Divide between plates along with tilapia and corn salad. Top tilapia with lime crema and remaining cilantro. Serve with remaining lime wedges on the side.