Sauté Garlic: Bring large cast-iron skillet to medium high heat. Add 1-2 tablespoons extra virgin olive oil, swirl to coat the pan. Add 1 tablespoon garlic and move around pan until it becomes fragrant, approx. 1 minute.
Onion + Peppers: Add ½ red onion (sliced), ½ yellow onion (sliced), 3 bell peppers and 2 tablespoons fajita seasoning. Stir to combine. Add additional olive oil to pan if you feel it is getting a bit dry. Sauté for approx. 10-15 minutes or until the peppers have reached your desired doneness (cook shorter for a more firm, but tender pepper - longer for a softer pepper).
Adjust: Taste and add any additional salt or pepper, to taste.