In a large bowl, combine beef, breadcrumbs, scallions, garlic, 1/2 cup chili sauce, egg, chili powder, cumin, 1 teaspoon salt, and 1/2 teaspoon pepper. Using your hands, mix just until combined; do not overmix.
Divide beef into 4 equal portions. Form each portion into a 4-inch-diameter patty, about 1 1/2 inches thick. Place on a plate; cover tightly with plastic wrap. Refrigerate until ready to use, up to overnight.
Preheat oven to 425 degrees with rack in center. Transfer patties to a rimmed baking sheet. Bake until browned, about 15 minutes.
Lightly brush tops and sides of patties with remaining 3 tablespoons chili sauce. Return to oven; cook until an instant-read thermometer inserted into center registers 160 degrees. 5 to 10 minutes more. Serve immediately, with tortillas, jalapenos, and radishes, if desired.