Heat the olive oil in a large skillet over medium-high heat.
Add the sliced steak to the skillet and cook for 2-3 minutes on each side, just until browned. This step adds extra flavor, but you can skip it if you’re in a rush.
Once seared, transfer the steak to the crock pot.
2. Add the Vegetables:
Add the onion, bell peppers, and garlic to the crock pot with the steak.
3. Prepare the Sauce:
In a small bowl, combine the soy sauce, beef broth, Worcestershire sauce, oyster sauce (if using), sugar, black pepper, and crushed red pepper flakes (if using). Stir well to combine.
Pour the sauce mixture over the steak and vegetables in the crock pot.
4. Cook:
Cover the crock pot with the lid and cook on low for 6-7 hours or on high for 3-4 hours, until the steak is tender and the flavors have melded together.
5. Thicken the Sauce:
About 30 minutes before serving, mix the cornstarch and water in a small bowl to create a slurry.
Stir the cornstarch mixture into the crock pot and cook for an additional 30 minutes on high until the sauce thickens to your desired consistency.
6. Serve:
Serve the pepper steak over hot, cooked rice or noodles. Garnish with chopped green onions or sesame seeds for added flavor and texture, if desired.
