Bell Pepper Soup with Sour Cream & Dill

1/4 cup olive oil
4 large bell peppers (2 pounds), stem, ribs and seeds removed and discarded; flesh diced*
1 medium Yukon Gold potato (8 ounces), diced
1 small onion, roughly chopped (to yield 1 cup)
1/2 teaspoon salt; more to taste
Generous pinch red pepper flakes
1 1/2 cups simmering vegetable or chicken stock; more if needed
Sour cream or crème fraiche for garnish
4 small sprigs fresh dill weed

* Red bell peppers will give the brightest color, but yellow or orange ones are just as delicious.

In a Dutch oven or a heavy stockpot, heat the oil over medium-high heat. Add the peppers, potato, onion, salt, and red pepper flakes. Cook, stirring, for 1 to 2 minutes. Reduce the heat to low, cover and simmer, stirring occasionally, until the vegetables are tender, about 1 hour. Remove from heat.

Transfer to a blender or food processor and puree in batches, or puree thoroughly with a hand immersion blender. Force the pulp through a coarse sieve or a food mill. Transfer to a saucepan and stir in the vegetable or chicken stock, adding a bit more if you like a thinner soup. Taste and adjust the seasonings.

Serve warm or cold, garnished with a dab of sour cream or crème fraiche and a sprig of dill.

Makes 4 servings (about 5 cups).