Slice the 300 g beef thinly against the grain.

Combine baking soda, 1 tbsp cornstarch, black pepper, 1 tbsp oyster sauce, 1 tbsp soy sauce, 1/2 tsp tamarind paste, and water in a mixing bowl.

Add the sliced beef to the marinade and coat it evenly.

Rest the marinated beef for 10 min.

Chop the garlic, slice the shallot and bell pepper, and cut the spring onions into 5 cm lengths.

Mix 1 tbsp oyster sauce, 1 tbsp soy sauce, 1/2 tsp tamarind paste, chili sauce, brown sugar, and apple cider vinegar until the sugar dissolves.

Sprinkle the remaining 1 tbsp cornstarch over the marinated beef and toss to coat.

Heat cooking oil in a wok over high heat.

Fry the coated beef in the hot oil until lightly crisp outside, about 1 min.

Remove the beef from the wok and set it aside.

Stir-fry garlic and dried red chili in the wok until fragrant, about 30 seconds.

Add shallot and bell pepper, then stir-fry until slightly softened, about 1 min.

Add half of the spring onions and toss for 30 seconds.

Return the fried beef to the wok and toss with the vegetables.

Pour in the prepared sauce and stir-fry over high heat until the beef is coated, about 1 min.

Add the remaining spring onions and drizzle in sesame oil.

Toss for 30 seconds and serve immediately with steamed white rice if desired.