Turn oven on to 400f and place rack in middle.
Chop garlic cloves. Slice zucchini on diagonal into 1/2" slices. Slice peppers and onions into 1/2" strips.
In a large bowl coat the peppers, onions, and zucchini with 1/4 cup of olive oil, 1/2 tsp oregano, 1/2 tsp salt, 1/4 tsp pepper and the chopped garlic. Mix well.
Spread the veggies onto a large sheet pan and roast in oven for 20 minutes.
While veggies are roasting zest 1 lemon and set aside. Squeeze lemons and collect 1/4 cup of juice. Combine the lemon juice with 1/2 cup extra virgin olive oil, 2 Tbsp of capers, and 1/4 tsp of salt. Mix well.
After twenty minutes turn off oven and turn on broiler. Broil the veggies for 3-5 minutes to crisp them up. Pay attention to not burn them.
After the veggies are crisp remove and plate. Spoon 2-3 Tablespoons of the lemon caper sauce over the veggies and sprinkle on the lemon zest.
Serve veggies with the remaining sauce on the side. Enjoy!