Preheat oven to 400 degrees F.

Cut head of cauliflower in half and then cut lengthwise into ¹⁄₂ inch thick slices (similar to cauliflower steaks). Toss cauliflower with 1 tablespoon olive oil, salt, pepper, crushed red pepper, and 1 teaspoon lemon zest. Lay in a single layer on a sheet tray and roast for 5 minutes.

While cauliflower is roasting, prepare shrimp by tossing with the remaining 1 tablespoon olive oil, garlic, and 2 teaspoons lemon zest.

Remove cauliflower from the oven after 5 minutes, push to the side, and add shrimp to the same sheet pan. Make sure shrimp is in an even layer. Return to the oven for an additional 8 to 10 minutes.

While shrimp and cauliflower are cooking, prepare the orange salsa. In a small bowl, dice the orange with the skin on and add the remaining ingredients. Toss shrimp and cauliflower with salsa.