Heat a pan on medium high heat and cook the ground beef, breaking it up as it cooks and adding ½ of taco seasoning. When browned, add red onion, peppers and remaining taco seasoning. Reduce heat.
Sprinkle with cheese and cover until melted.
Garnish with green onion; season with chili flakes, salt and pepper, to taste. Serve with salsa and guacamole.