Combine juice and rinds of the lemons and limes along with the oil, garlic, onion, and spices in a large Ziploc bag. Add sirloin strips and marinate overnight or for at least a few hours.
Heat a large saute pan over medium-high heat. Spray cooking spray then sear marinated steak (discard marinade along with fruit). Remove from pan and set aside.
In the same pan, add more cooking spray and saute bell peppers and onions until soft, about 5-10 minutes. Add steak back into skillet and heat through.
Notes
Click here to determine your WW PersonalPoints for this recipe (if you are logged in to your WW app, it should calculate for you automatically). Serving size is ~ 2/3 cup.WW Freestyle SmartPoints: 3 per serving (about 2/3 cup)*Most of the marinade gets thrown away, so I don't count the oil. If you want to be safe, you can add an extra point to the serving, making them 4 SP.