- 1 large leek (white and pale green parts only), washed and thinly sliced (2 cups)
- 1 celery rib, cut into 1/2-inch pieces
- 1 large carrot, cut into 1/2-inch pieces
- 1 garlic clove, finely chopped
- 1 large thyme sprig
- 2 tablespoons extra-virgin olive oil
- 1/2 pound boiling potatoes, peeled and cut into 1/2-inch pieces
- 1/2 pound Swiss chard, stems cut into 1/2-inch pieces and leaves coarsely chopped
- 8 cups water
- 2 cups thawed frozen edamame (fresh soybeans)
- 1/2 pound zucchini, cut into 1/2-inch pieces
- 1/4 pound green beans, trimmed and cut into 1-inch pieces
- 3/4 cup medium pasta shells
- 1 small tomato
- 1 cup packed basil leaves
- 1/2 cup packed flat-leaf parsley leaves
- 2 garlic cloves, finely chopped
- 2 tablespoons extra-virgin olive oil
- 1 cup coarsely grated Gruyère (3 ounces)
- Accompaniment: grilled baguette slices brushed with olive oil
- Cook leek, celery, carrot, garlic, and thyme sprig in oil with 1/2 teaspoon salt and 1/4 teaspoon pepper in a 5-to 6-quart heavy pot over medium heat, stirring occasionally, until vegetables brown and stick to bottom of pot, 10 to 15 minutes.
- Add potatoes and chard stems with 1/2 teaspoon salt and cook, stirring occasionally, until beginning to soften, about 5 minutes. Add water and bring to a boil, stirring and scraping up brown bits.
- Stir in edamame, zucchini, green beans, pasta, chard leaves, and 1/4 tsp salt and simmer, uncovered, until pasta is al dente and vegetables are tender, about 10 minutes. Discard thyme sprig.
- Heat a dry small skillet (not nonstick) over medium heat until hot, then char tomato on all sides. Core tomato, then purée with basil, parsley, and garlic in a food processor. Add oil and cheese and blend well.
- Remove soup from heat and stir in half of pistou and salt and pepper to taste. Serve soup with remaining pistou.