Heat a large nonstick skillet over medium-high heat. In a food processor, add bell pepper, zucchini, carrots, onion, and garlic. Pulse until the vegetables are finely minced.*
Spritz skillet with cooking spray. Add vegetables along with 1/2 tsp salt. Sauté until veggies are soft and onion is translucent, about 6-8 minutes. Transfer veggies to a medium-sized bowl and allow to cool.
Once the veggies are cooled to room temperature, add ground turkey, egg, panko, parmesan, remaining salt, oregano, pepper flakes, and black pepper. Mix until just combined. Put mixture in the freezer for about 5-10 minutes to firm up a bit.
Wipe out the same large skillet and return to medium-high heat. Divide meat mixture into 6 oval loaves. If meat mixture is still loose, wet your hands with water before forming loaves so the mixture doesn't stick to them.
Spritz skillet with cooking spray and add the loaves. Brown about 3 minutes per side.
Add 1/2 cup water or stock to the skillet, cover, and simmer over low heat until loaves are firm and just cooked through, about 10 minutes.
Transfer loaves to a plate. Add the ketchup and mustard to the skillet. Whisk and and cook over medium-high heat. stirring, until slightly thick--about 2-3 minutes.
Return loaves to skillet, remove from heat, and spoon glaze on top.