Remove beef from fridge 30 minutes prior to cooking. Pat dry. Season with salt and pepper.
In large Dutch oven, heat 1 tablespoon of vegetable oil over medium high heat. Add in half of the pieces of beef. Sear for about 1 minute, then turn on another side and continue cooking for 1-2 minutes, getting deep brown color on the beef. Remove beef from pan and set aside.
Add ½ tablespoon oil to pan repeat with remaining beef tips.
Once the second batch is seared off, take it out of the pan and set aside with the rest of the beef, reduce heat to medium and add butter. Once it begins to foam, add onions, bell pepper. Season with salt and pepper. Cook until almost tender, about 4 minutes. Add garlic and thyme and cook for an additional minute.
Sprinkle flour over vegetables. Using a wooden spoon, stir to make sure flour is fully hydrated and coating the vegetables.
Slowly pour in beef broth, about half cup at a time, scraping the bottom to release the brown bits and stirring constantly to keep the gravy smooth. Do not add broth all at once.
Increase heat to medium high and bring to a boil. Add beef tips and any juices. Add Worcestershire sauce and reduce heat to a simmer, allowing beef to finish cooking and gravy to thicken, about 40-50 minutes.
Stir in parsley and serve over cooked rice.