In a large bowl, mix the zucchini, onion, garlic, red pepper, breadcrumbs, 1/4 cup Harissa, egg, paprika and salt.
Add the turkey and combine until mixed through.
Form the meat into 5 round patties.
Combine the remaining 1 1/2 tbsp Harissa with the ketchup in a small bowl.
Heat a large skillet over medium. Spray with oil and cook covered until cooked through, about 8 to 10 minutes per side, reducing the heat if they start to get too browned.
Brush the Harissa-ketchup mixture on top during the last few minutes of cooking.