Prepare the Sauce: In a small bowl, whisk together all the sauce ingredients: oyster sauce, light soy sauce, dark soy sauce, fish sauce, sugar, and water. Set this aside.

Sauté the Aromatics: Heat 1 tbsp of oil in a large frying pan or wok over a medium-high heat. Add the minced garlic, chopped chillies, and diced shallot. Stir-fry for 1-2 minutes until fragrant and the shallot has softened slightly.

Cook the Beef: Add the beef mince to the pan. Use a wooden spoon to break it up into fine pieces. Cook for 5-7 minutes, stirring frequently, until the beef is browned all over and no pink remains. Drain off any excess fat from the pan.

Combine with Sauce: Pour the prepared sauce mixture over the cooked beef. Stir well to combine and let it simmer for 2-3 minutes, allowing the beef to absorb all the flavours and the sauce to thicken slightly.

Add the Basil: Remove the pan from the heat. Stir in the fresh Thai holy basil leaves. The residual heat will wilt them perfectly while preserving their intense aroma.

Cool the Filling: This is a crucial step! Transfer the beef filling to a bowl and spread it out. Allow it to cool completely to room temperature. A warm filling will make the wrappers steam and tear.

Assemble the Rolls: Lay a spring roll wrapper on a clean surface in a diamond shape. Place about 2-3 tablespoons of the cooled filling in a line near the bottom corner. Fold the bottom corner up over the filling. Fold in the left and right sides tightly, then roll it up towards the top corner. Dab the final corner with a little water to seal it shut. Repeat with the remaining wrappers and filling. I find that keeping the wrappers under a slightly damp tea towel prevents them from drying out as I work.

Fry the Rolls: Pour the vegetable oil into a deep saucepan or wok until it is about 5cm deep. Heat the oil to 180°C. You can test if it's ready by dropping a small piece of wrapper in; it should sizzle and turn golden in about 30 seconds. Carefully place 3-4 rolls into the hot oil, making sure not to overcrowd the pan.

Fry Until Golden: Fry the rolls for 3-4 minutes, turning them occasionally, until they are deep golden brown and crisp all over.

Drain and Serve: Use a slotted spoon to remove the rolls from the oil and place them on a wire rack to drain. This keeps them crispy. Serve immediately with your favourite dipping sauce.