Add chicken breast into a large bowl and sprinkle with salt and pepper.

Cut green peppers in half and add into bowl.

Add juice from both lemons into the bowl along with olive oil.

Cover and let marinate for at least 2 hours in the fridge or overnight.

Grill marinated chicken and peppers on medium high heat for about 5 minutes each side. The internal temperature of the chicken should be at least 165 degrees Fahrenheit.

Shred and dice chicken and peppers and add on top of warm tortilla shells with diced onion and cilantro.