Marinate the tofu cubes in the ginger teriyaki sauce with some ½ tsp garlic and sesame seeds. You can do this hours in advance and store in the fridge. But keep it marinated for at least 30 minutes.
Boil the udon noodles as per its packet instructions and set aside.
Sauté the spinach and spring onions in 1 tsp vegetable oil and 1 tsp garlic, until gently wilted.
Heat a non-stick pan on high heat. Grill the tofu on the pan.
In the serving plate, place the noodles first, then the spinach on top and the tofu on top.
Garnish with some chopped red chillies and spring onions.
Stir the sauce ingredients together and serve on the side.