Melt schmaltz in a large skillet over medium-low. Cook oregano sprigs, rosemary sprigs, garlic, and red pepper flakes, tossing, until fragrant, about 1 minute. Add matzo to skillet and cook, stirring, until toasted and khaki-colored, about 5 minutes. Transfer to paper towels; season with salt. Remove herbs from stems; discard stems. Let cool. Use like croutons.
