Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Cook turkey sausages until they begin to brown and firm up, 3 to 4 minutes per side. Remove to a cutting board and let cool slightly before cutting into 1/2-inch thick diagonal slices; they will not be completely cooked at this point.

Heat remaining 1 tablespoon oil in the same skillet over high heat. Quickly stir-fry onion until it begins to brown, about 1 minute. Add peppers and continue cooking over high heat, stirring constantly, until peppers begin to brown, 2 to 3 minutes. Do not overcrowd the skillet in order to get a nice char on vegetables. Mix in garlic and cook for 1 minute.

Return sausage, and any accumulated juices, to the skillet. Season with crushed red pepper, salt, and pepper and reduce heat to medium. Stir to combine and continue cooking until sausage is no longer pink in the center, about 2 minutes more.