Heat up 2 Tablespoons vegetable oil in a large skillet over high heat. You want to get that oil really heated up. It should be very hot.
Season 2 pounds steak, cut into 1-inch strips with 1 teaspoon garlic powder and salt and pepper, to taste.
Carefully place half the beef strips into hot pan. Brown beef strips on both sides. They should be sizzling when you put them in the pan. It should only take about a minute per side. Do not cook through, just brown the outside.
Continue with the other half of the beef strips. Once they are all browned, transfer beef to crock pot.
In a small bowl, crush and mix 1 beef bouillon cube with 1/4 cup hot water until dissolved. Then stir in 1 Tablespoon cornstarch until dissolved. Pour this slurry into the crock pot with the beef.
Add 15 ounce can stewed tomatoes with juices, 3 Tablespoons teriyaki or soy sauce, 1/2 teaspoon red pepper flakes and 1 teaspoon sugar.
Give it all a quick stir. Then cover and cook on on low for 6 to 8 hours.
During the last hour of cooking, add in 1 large green pepper, cut into strips, 1 large red pepper, cut into strips and 1 small yellow onion, sliced. Cover and cook for additional hour. Then serve.
Video
Notes
Remember when cutting steak to always cut against the grain for the most tender cut of meat.
Short on time? Just purchase fajita meat so the beef is already cut for you! Some stores even have sliced peppers and onions in the produce section as well.
If you want the sauce in this to be even thicker, just add another cornstarch slurry (at the end) to it. Mix a Tablespoon of water with a Tablespoon of cornstarch. Add to the crock pot, stir, then turn on high and cook until thickened.
Serve it on top of rice or in flour tortillas as fajitas.
Can't find beef bouillon? Just substitute beef stock or substitute the powdered beef bouillon with the Better than Bouillon beef paste.