In a large pot, heat the olive oil1/4 over medium heat. Add the onion1, carrot2, celery, 1/2 teaspoon salt1/2, oregano1/2, black pepper1/2, and red pepper flakes1/4. Cook, stirring occasionally, until the vegetables have just softened, about 7 minutes. Add the garlic; cook, stirring often, about 2 minutes more.