Beef Teriyaki Udon Noodles

Grocery List 20 oz sliced beef rib steak or sirloin tip steak2 tbsp soy sauce2 tbsp olive oil200 g Udon noodles½ cup spinach½ sliced celery ½ slice red bell pepper ½ cup sliced mushroomsGreen onions, chopped for garnish (optional)Roasted sesame seeds (optional) Teriyaki sauce ¼ cup soy sauce¼ cup brown sugar¼ cup mirin1 tsp cornstarch [...]