Marinate the Beef

• Slice the beef into thick pieces, cutting against the grain.
• Place in a bowl and add oyster sauce, sesame oil, and soy sauce. Mix well and let marinate for 15 minutes.

Prepare rice noodles according to package directions.

Stir-Fry the Beef

• Heat peanut oil in a wok or large frying pan over high heat.
• Drain the beef, reserving the marinade.
• Once the oil is just starting to smoke, add the beef and stir-fry for 2 minutes. Remove and set aside.

Cook the Vegetables

• Wipe the pan clean with a paper towel.
• Reheat the wok on high heat and add a little more oil.
• Add spring onions, carrots, and mushrooms, stir-frying for 3–4 minutes.

Combine & Simmer

• Add bell pepper, rice noodles, and water with the reserved marinade.
• Cover and let simmer for 2–3 minutes.

Finish & Serve

• Remove the lid and return the beef to the wok, stir-frying for another 3–4 minutes until fully cooked.
• Stir in the baby spinach and cilantro until just wilted.