1.Slice the beef into thin slices. Place in a bowl and add 4 tsp. of soy sauce, 1 tablespoon of rice wine, 1 teaspoon of buckwheat flour and season with freshly ground black pepper.
2.In a small bowl, mix 3 tablespoons of soy sauce, 1 tablespoon of water and 2 tsp. buckwheat flour, then set aside.
3.Heat 1 teaspoon of oil in a pan on high heat. Add the beef and cook for around 20 seconds letting the beef brown. Next, stir the meat, cooking another 2 minutes and transfer onto a plate.
4.Add the remaining 1 teaspoon of oil to the pan, add the peppers and onions and cook about 4-5 minutes. Place the beef back into the pan, add the prepared sauce and red pepper flakes (optional). Stir fry for about 30-60 seconds on medium heat until slightly thickened.
5.Serve with rice (not included in nutrition info per serving).
6.Store in the fridge for up to 4 days

12 oz. (340g) round beef, trimmed
4 tsp. plus 3 tbsp. soy sauce
1 tbsp. rice wine
3 tsp. buckwheat flour
2 tsp. coconut oil
1 large onion, sliced into strips
1 red bell pepper, sliced into strips
½ tsp. black pepper
crushed red pepper flakes, to taste

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