Step 1 : In a small bowl, combine all ingredients for the spice blend. Toss the strips of onion and peppers with 1 tablespoon oil, making sure the vegetables are all evenly coated with oil.
Step 2 : Divide the vegetables onto two large, parchment-lined baking sheets, spreading the veggies out so they're not piled on top of each other. Roast vegetables for 7-8 minutes.
Step 3 :Return baking sheets to the oven and continue roasting for about 5 minutes more, until the shrimp are opaque and just cooked through. Check carefully to be sure the shrimp don't overcook.