1 tablespoon vegetable oil, or as needed
1 pound kielbasa (Polish) sausage, halved lengthwise and sliced
1/2 sweet onion (such as Vidalia®), diced
6 miniature multi-colored sweet peppers, diced
1 teaspoon dried oregano
1 teaspoon dried thyme
1/2 teaspoon cayenne pepper
1/4 teaspoon celery salt
1 pinch red pepper flakes
1 cup quinoa
2 cups chicken broth
1/2 cup marinara sauce
1Heat oil in a large skillet over medium heat; cook and stir sausage until browned, about 5 minutes. Add onion to sausage; cook and stir until slightly browned, about 5 minutes. Stir sweet pepper, oregano, thyme, cayenne pepper, celery salt, and red pepper flakes into sausage mixture; cook and stir until fragrant, 1 to 2 minutes.
2Mix quinoa into sausage mixture; cook and stir until quinoa is slightly toasted, about 1 minute. Pour broth and marinara sauce over quinoa mixture. Cover skillet and simmer until quinoa is tender, about 15 minutes.