Japchae Korean Beef Stir-Fry with Glass Noodles

Ingredients

• 1 lb. Strip Steak, sliced very thinly against the grain
• 5 Tbsp. low-sodium soy sauce or tamari
• 2 Tbsp. rice vinegar
• 1 Tbsp. light brown sugar
• 1 Tbsp. toasted sesame oil, divided
• 1 (7 oz.) package sweet potato glass starch noodles, cooked according to package instructions, drained and kept warm
• 2 bell peppers (any color), cored, seeded, and sliced
• 2 cloves garlic, finely chopped
• ½ medium yellow onion, sliced
• 1 ½ cups matchstick or julienned carrots
• 6 oz. shiitake or button mushrooms, sliced
• 2 cups baby spinach
• 1 Tbsp. toasted sesame seeds

Optional ingredients

• Additional soy sauce, to taste
• Gochujang, to taste