broccoli soup with lemon chive cream

Oh, and should you have some of the sour cream mixture left over, it makes a great dip for potato chips.

For the soup:
1 Tbsp. unsalted butter
1 Tbsp. olive oil
2 medium leeks, white and tender green parts only, sliced
1 small yellow onion, coarsely chopped
3 cloves garlic, coarsely chopped
1 ½ lb. broccoli, both crowns and stems, trimmed and coarsely chopped
5 cups chicken or vegetable stock
1 rind (about 2 inches square) from a piece of Parmesan cheese
¾ tsp. kosher salt, or less if your broth is well salted

For the sour cream:
1 cup sour cream (not low-fat or nonfat)
2 scallions, white and pale green parts only, very thinly sliced
¼ cup minced chives
1 tsp. grated lemon zest
2 Tbsp. fresh lemon juice
½ cup finely grated Parmesan cheese
½ tsp. kosher salt
¼ tsp. pressed or minced garlic

In a small stockpot or Dutch oven, warm the butter and oil over medium heat. Add the leeks and onion, and cook, stirring occasionally, until they have softened and the onion is translucent, about 10 minutes. Add the garlic, and cook for one minute. Add the broccoli, stock, Parmesan rind, and salt, and stir to mix. Bring to a boil, reduce to a simmer, and cook, partially covered, until the broccoli is tender, about 20 minutes.

While the soup cooks, prepare the cream. In a medium bowl, stir together the sour cream, scallions, chives, lemon zest, lemon juice, grated Parmesan, salt, and garlic, mixing until fully combined. Taste, and adjust as necessary.

To finish the soup, remove the Parmesan rind. Using a blender and working in small batches – when puréeing hot liquids, never fill the blender more than one-third full – purée until very smooth. (Alternatively, purée it in the pot with an immersion blender.) Return the soup to the pot, add a few dollops of the cream mixture – I add about 1/3 cup – and stir to incorporate. Taste for seasoning, and adjust as necessary. If needed, rewarm the soup gently over low heat.

Serve the soup with a spoonful or two of the remaining cream on top.