Step 1: Prepare the Beef

1. Thinly slice the beef into strips, about ¼ inch thick. For easier slicing, freeze the beef for 15-20 minutes beforehand.
2. In a large mixing bowl, combine the cornstarch, garlic powder, smoked paprika, salt, and black pepper.
3. Toss the beef strips in the cornstarch mixture, ensuring each piece is evenly coated. For extra crispiness, dip the coated beef in beaten egg before dredging in a second layer of cornstarch.

Step 2: Fry the Beef

1. Heat the vegetable oil in a large skillet, wok, or deep pan over medium-high heat. The oil should be hot but not smoking, around 350°F (175°C).
2. Fry the beef strips in batches, being careful not to overcrowd the pan. Cook for 3-4 minutes per batch, or until the beef is golden brown and crispy.
3. Use a slotted spoon to transfer the fried beef to a plate lined with paper towels to drain excess oil. Repeat with the remaining beef.

Step 3: Make the Chilli Sauce

1. In a small bowl, whisk together the soy sauce, rice vinegar, honey, ketchup, sweet chili sauce (if using), and red chili flakes. Set aside.
2. In a separate bowl, dissolve the cornstarch in water to create a slurry.

Step 4: Stir-Fry the Vegetables

1. Remove excess oil from the skillet, leaving about 1 tablespoon. Heat the skillet over medium heat.
2. Add the minced garlic, grated ginger, and julienned carrots. Stir-fry for 1-2 minutes until fragrant.
3. Add the sliced red and green bell peppers and stir-fry for an additional 2-3 minutes, or until the vegetables are slightly tender but still crisp.
4. Stir in the green onions and cook for 30 seconds.

Step 5: Combine the Beef and Sauce

1. Reduce the heat to low and return the crispy beef strips to the skillet with the vegetables.
2. Pour the prepared chilli sauce over the beef and vegetables. Stir well to coat everything evenly.
3. Add the cornstarch slurry to the skillet, stirring continuously until the sauce thickens and glazes the beef and vegetables. This should take 1-2 minutes.

Step 6: Serve and Garnish

1. Transfer the Crispy Chilli Beef to a serving platter or bowl.
2. Garnish with sesame seeds, chopped green onions, or fresh cilantro for added flavor and presentation.
3. Serve immediately with steamed white rice, fried rice, or noodles.