- Mix together all the ingredients for the marinade in a bowl. 
- Pour marinade over beef slices, toss until beef is evenly coated. Be gentle as you don't want to tear the slices. Let beef marinade in the fridge for 15-30 minutes. 
- Meanwhile, cut the roots off of the enoki mushrooms. Then, break into smaller bunches. 
- On a clean bench or large plate, spread out one slice of beef and place enoki mushrooms on one end. Roll up tightly. Repeat for the remaining beef and enoki mushrooms. 
- Heat up a nonstick skillet over medium heat. Add enoki beef rolls and cook for 1 minute. Keep rotating and searing until beef is browned on all sides. 
- Transfer enoki beef rolls to serving plate and garnish with sesame seeds and chopped spring onions if desired. Serve immediately.