4 cups water
1 veggie broth cube
1/2 package of firm tofu, drained, cut into cubes
1/2 onion, chopped
2 bunches of soba noodles
1 cup dried shiitake mushrooms reconstituted in 1 cup water
1/4 cup soy sauce
Re-constitute the mushrooms in a small bowl or cup with water. Let it sit there while you make the other stuff.
Pre-cook 2 bunches soba noodles (for some odd reason, soba noodles, at least the Japanese brands do this, are packaged in smaller bunches inside a main package. Each packet has a little band around it). Drain the noodles and set them aside.
Fry the onion in the bottom of a stock pot in a 2 teaspoons of oil over medium heat. Douse the onions with 4 cups water and add the broth cube. Bring it up to hot but not boiling. Add the mushrooms with their water, the drained soba noodles, and the soy sauce. Add the tofu, simmer until heated through. To serve, heap a generous handful of spinach in a bowl and pour the soup over it.