Remove cilantro leaves and chop

Cover and set aside

Thinly slice onion lengthwise

Cut red pepper into julienne strips

Cut steak across the grain into 3 inch long thin strips

Heat olive oil in a large skillet over medium heat

Add onion and red pepper and cook until very tender, about 8 minutes

Remove to a plate

Raise the heat to medium high and add the streak strips

Toss until no longer pink, about 2 minutes

Return pepper and onions to skillet and add the corn, cumin and chili powder

Toss until heated through, seasoning with salt and pepper to taste

Serve in warmed tortillas topped with guacamole and grated cheese.