Step 1: Marinate the sliced beef with soy sauce, oyster sauce, fish sauce, minced garlic, and brown sugar for 15 minutes.

Step 2: Heat vegetable oil in a large skillet over medium-high heat and stir-fry the marinated beef for 3-4 minutes until just cooked through.

Step 3: Remove beef from heat and let cool for 5 minutes while preparing vegetables.

Step 4: Soak one rice paper round in warm water for 30 seconds until pliable, then lay flat on a clean surface.

Step 5: Place 3-4 pieces of cooked beef in the center of the rice paper, leaving 2 inches on all sides.

Step 6: Add 4-5 Thai basil leaves, a few cucumber strips, carrot julienne, and bell pepper slices on top of the beef.

Step 7: Fold the bottom edge over the filling, fold in the sides, then roll tightly from bottom to top.

Step 8: Repeat with remaining rice papers and filling ingredients, keeping finished rolls covered with damp paper towels.

Step 9: Slice each roll in half diagonally before serving with your favorite Thai dipping sauce.