Put a little water in the bottom of your pan, and turn on to medium-high heat.

Add onions, mushrooms, and peppers and keep an eye on the pan, letting the vegetables saute, stir occasionally so they do not stick to bottom of the pan. If water starts to run out before vegetables are tender, add a little more.

Meanwhile, cook chicken breast (I used a George Foreman grill), season with salt and pepper if desired.

Chop chicken into strips, and add into vegetables, turn heat up, and let onions caramelize, but don't let them burn.

Season as desired

Serve inside lettuce leaves, and top with fresh avocado, cheese, sour cream, or salsa as you see fit