Clear Soup With Sweet Potatoes, Silken Tofu, and Mustard Greens

From "This Can't be Tofu!" by Deborah Madison.

• Ready In: 40 mins
• Serves: 4

Ingredients

• 2  tablespoons  vegetable oil
• 2  teaspoons  sesame oil
• 1  tablespoon garlic, coarsely chopped
• 1  tablespoon ginger, chopped
• 1  large jalapeno chile, diced, seeds left in for more heat (optional)
• 1⁄4 cup cilantro stems, thinly sliced
• 6  cups  chicken stock or 6  cups vegetable broth
•  five-spice powder, to taste
• 1  teaspoon salt
• 12  ounces sweet potatoes, peeled and diced into 1/2-inch cubes
• 3  cups  mustard greens, stems discarded and leaves cut into ribbons
• 1 (12 -15 ounce) box silken tofu or 1 (12 -15 ounce) box soft tofu, cubed
• 2  scallions, diced
•  soy sauce, to taste

Directions

1. heat vegetable oil and half of sesame oil in soup pot. when hot, add garlic, ginger, chile, and cilantro. stir-fry for 2 minutes. add broth, five-spice powder, and salt. bring to a boil, then lower the heat and simmer, covered, for 15 minutes. strain and return to the pan, or simply lift out the chopped flavorings with a small skimmer. press out as much liquid as you can, then discard.
2. add sweet potatoes to the pot and simmer, covered, for 10 minutes or until tender when pierced with a knife.
3. add greens and tofu. cook gently, uncovered, until the greens are bright and tofu is hot, about 5 minutes. add scallions. taste for salt and add remaining sesame oil. add soy sauce to taste, if dish seems to need a little extra punch.