To prepare sauce, combine first 5 ingredients in a small bowl. Set aside.
To prepare cakes, place green bell pepper and the next 4 ingredients (through onion) in a food processor; pulse until minced. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add bell pepper mixture; sauté 5 minutes or until vegetables are tender. Remove from heat; cool completely. Wipe pan clean with a paper towel.
Place bread in food processor; process until coarse crumbs measure 1 cup. Chop 1 pound of fish into 1/4-inch pieces; place in a large bowl. Chop remaining 1/2 pound fish; place in food processor. Pulse until finely minced; add to chopped fish. Add bell pepper mixture, breadcrumbs, 1 3/4 teaspoons salt, 1/2 teaspoon black pepper, orange rind, and egg whites to fish mixture; stir until well blended.
Divide fish mixture into 24 equal portions, shaping each into a 1/2-inch-thick patty. Heat 1 teaspoon oil in pan over medium-high heat. Add 6 patties; cook 2 1/2 minutes on each side or until browned. Transfer patties to a baking sheet coated with cooking spray. Repeat process 3 times with remaining oil and patties. Bake at 400° for 10 minutes or until cooked through. Serve with sauce.