Clean the cabbage, remove the outer leaves, and slice the cabbage into thick, about 1 inch wide strips.
In a large non-stick pan over medium-high heat add the oil. Once the oil is hot, add garlic, ginger, and red pepper flakes and stir. Cook for about 30-60 seconds.
Add the Napa cabbage, soy sauce, hoisin sauce, paprika, sugar, and vinegar. Stir-fry for about 7-8 minutes, until the cabbage softens.
Add chopped green onions. Stir and cook for 1 minute.
Transfer the cabbage onto a serving platter, drizzle with sesame oil and garnish with sesame seeds and chopped green onions.