Step 1 Bring 6 cups of water to a boil, remove from heat and cool slightly. Add the tea, konbu and ginger, and set aside to steep for 10
Step 2 minutes.
Step 3Meanwhile, sauté the mushrooms in the sesame oil until golden brown, then remove from heat and hold in a warm place.
Step 4Strain the broth into a small pot. Add the udon to the broth and bring to a boil. When the noodles froth up, add a cup of cold water. When the water returns to a boil, reduce the heat to a gentle simmer until the noodles are cooked.
Step 5Divide the cooked noodles between two bowls. Briefly blanch the spinach in the hot broth, then strain. Add a few cups of broth to each bowl, then top with the mushrooms, spinach and scallions. Drizzle with soy sauce as desired and garnish with sesame seeds. Serve immediately.