Prep your veggies. Peel and slice the onion. Deseed and slice the peppers into medium-sized strips.
Add the onions and a pinch of salt to a skillet over medium heat. Cook for 2 to 4 minutes, or just until they start to smell aromatic.
Add the bell peppers, seasonings, and a few tablespoons of water (or oil) to the skillet. Turn the heat up to medium-high and cook for 10 to 15 minutes, deglazing the skillet as needed with a splash of water.
Remove from the heat and add a squeeze of lime juice and a sprinkle of cilantro. Serve and enjoy right away or store for later!
If you are cooking without oil: As the fajita veggies cook, keep a small cup of water nearby so that you can deglaze (add a splash of water) to the skillet if the veggies start to stick. Deglazing the skillet will also release any seasonings from the surface of the skillet and add them back to your veggies.