Season steak lightly with fajita seasoning. Add steak, soy sauce and marinade into a ziploc bag. Seal, massage marinade into steak, and put into the fridge for 25 minutes. Take bag out of fridge and let rest on the counter for about 5 minutes
Slice flank steak AGAINST the grain. Slices should be about 1/4", so meat will cook quickly.
Add quinoa to a cold pot. Over medium-low heat, toast quinoa for a few minutes, to release the natural oils and nutty flavor. Add broth, bring to a boil, reduce to a low simmer, and cook for about 18 minutes. Remove and add to a large bowl.
In a skillet over medium heat, add corn and saute for about 5 minutes. Add jalapeno and continue to saute for another 3-4 minutes. Add bell peppers and red onions, and saute for 3-4 minutes.
Remove vegetables from skillet, and combine with black beans and quinoa
In same skillet over medium-high heat, add steak. Cook steak for about 2 minutes per side. Remove, and add to quinoa mixture
Add avocado and fresh lime juice to quinoa mixture. Combine fully, and serve. ENJOY!