Prepare the marinade by combing all ingredients except the olive oil, then whisk in olive oil.
Remove fatty membrane from steak. Place steak in a plastic freezer bag and set aside.
Place shrimp in a plastic freezer bag and set aside.
Cut chicken into thin strips. Place in a separate plastic freezer bag. Split marinade between the three bags.
Squeeze as much air out of the bags as possible, seal, and chill in the refrigerator for at least 30 minutes, up to 24 hours.
Preheat skillet over medium-high heat, or preheat grill.
Cut bell pepper and onion into medium-sized chunks.
Drizzle pan with olive oil, or coat grill basket in high-heat cooking spray. Saute veggies until caramelized. Set aside, but keep warm.
Add steak to the pan and cook undisturbed for 2 minutes. Flip and cook the other side for 2 minutes. Flip again and cook each side again for about 2 minutes.
Remove steak from the pan and let it rest, or transfer to indirect heat on the grill. (This cooked them to medium. Consuming raw or undercooked meats, poultry, seafood, shellfish, or eggs may increase your risk of foodborne illness, especially if you have certain medical conditions. Refer to USDA guidelines.)
Cook the shrimp and set aside, keeping warm.
Cook the chicken. While the chicken is cooking, slice the skirt steak.
Return everything, including veggies, to the pan or grill basket and cook together for no about 1 minute.
Serve with warm tortillas, sour cream, and guacamole.