2 tablespoons olive oil
2 teaspoons freshly ground yellow mustard seeds (1 teaspoon seeds)
4 cups watercress leaves
4 cloves garlic, crushed into a paste
1 teaspoon dried tarragon, finely crumbled
1 teaspoon dried marjoram, finely crumbled
1 teaspoon freshly grated nutmeg
1 teaspoon freshly ground white pepper (1/2 teaspoon peppercorns)
2 cups vegetable stock
1 cup peeled potato chunks, simmered in water to cover until tender and drained
1 tablespoon mellow (light-colored) miso
1/2 teaspoon Vege-Sal or 1/4 teaspoon salt, or to taste

1. Heat the olive oil in a large skillet over medium heat, add the ground mustard seeds and cook, stirring constantly, until the seeds pop, 1 to 2 minutes. Add the watercress, garlic, tarragon, marjoram, nutmeg, and pepper and cook, stirring, for 5 minutes.

2. Carefully transfer the cooked watercress mixture to a blender, add the remaining ingredients, and process until smooth, holding down the blender cover with a towel at first to prevent eruption. Reheat gently if necessary.

Serves 4 to 6