To create bulgogi marinade, add soy sauce, water, sweetener, garlic, and sesame oil and blend in a blender until smooth.
Mix blended ingredients with beef and marinade for at least 15 minutes before cooking in a pan or grilling.
As beef marinades, thinly slice radish and cucumber and sprinkle with 1 tbsp of gochugaru, juice of 1 lemon, add salt to taste, and mix together.
Thinly slice zucchini. In a pan on medium heat, add sesame oil and stir fry zucchini until lightly browned on both sides. Separately, do the same for the greens from the radish.
Bring water to a boil. Once water is boiling, stir in couscous, oil, and salt. Cover with lid and reduce heat to low and let simmer for 8-10 minutes.
In a wide pan, cook bulgogi without overcrowding the pan, until browned on both sides.
Once bulgogi beef is ready, assemble bowl by combining couscous, banchans, and bulgogi and top with toasted sesame seeds and serve immediately.