Preheat oven to 450 F. Line a baking sheet with foil. Cut 3 medium potatoes into 1-inch pieces. Toss with 2 tbsp olive oil, salt, and pepper. Spread out evenly on the lined sheet and bake in oven 10 minutes. Remove kernels from 3 ears corn by placing corn upright on a cutting board, flat end down, holding securely at the top, and cutting down the sides. Cut 2 medium zucchini or yellow squash into 1-inch pieces. Toss zucchini and corn kernels with 3 tbsp olive oil; season with salt, and pepper. Once potatoes have baked 10 minutes, add veggies to same sheet, placing around potatoes, then return to oven and bake 8 minutes more. Meanwhile, cut three 6-8 oz swordfish steaks into 1 1/2-inch cubes and coat in in 1 tbsp olive oil; season with salt and pepper. For a spicier flavor, also coat in 3 tbsp harissa. Take 12 shishito peppers and coat them in 1 tsp olive oil and salt. Remove sheet from oven after 8 minutes and add swordfish and peppers. Bake until fish is cooked and veggies are tender, about 8 minutes. Let rest a few minutes before serving.