Wash leeks, green onions, and mushrooms. Peel ginger and dice. Cut green onion, leeks, chili (only if you want to make it spicy), and mushrooms into thin slices. Rinse cutting board and cut the chicken into small cubes.

Heat up 4 cups of water in a pot. When boiling, add Chow mein noodles and cook at medium heat for 5 minutes. Drain noodles and set aside.

Heat up sesame oil in a pan. Add ginger, garlic, chili (only if you like spicy food) and chicken cubes. Sauté for about 10 minutes until chicken is fully cooked and turns golden brown.

Add mushrooms, 90% of the leeks and green onions. Sauté for another 3 minutes and mix ingredients well.

Finally, add the noodles, sesame seeds, rice vinegar, and tamari sauce. Sauté ingredients for 2 minutes to make sure they are mixed well.

Place noodle mix in a bowl. Garnish with remaining green onion and leek slices. Sprinkle sesame seeds on top.