Ingredients
2 T extra-virgin olive oil
1 T unsalted butter
1 large yellow onion, finely chopped (about 1 ¼ cups)
1 large garlic clove, smashed and peeled
2 T all-purpose flour
3 c lower-salt chicken broth
28-oz. can whole peeled plum tomatoes, pureed with the juice (preferably San Marzano)
1 ½ t sugar
½ t fresh thyme leaves or ¼ t dried thyme
Kosher salt and black pepper
½ c plain yogurt (you can substitute sour cream or crème fraiche)
1 T minced basil
1 T minced scallion
½ T prepared white horseradish
Preparation
In a non-reactive Dutch oven, heat oil and butter over medium-low heat until butter melts. Add onion and garlic; cook, stirring occasionally, until soft but not browned, about 8 minutes. Add flour; stir to coat onion and garlic.
Add broth, tomatoes, sugar, thyme, ½ t salt, and ¼ t pepper. Bring to a simmer over medium-high heat, stirring to make sure flour does not stick. Reduce heat to low; cover and simmer for 40 minutes.
While soup cooks, mix yogurt, basil, scallion, and horseradish. Season to taste with salt and black pepper.
Cool soup briefly, then puree in 2-3 batches in blender. Return soup to clean pot and keep warm. Season to taste with salt and pepper.
Ladle into bowls and garnish with a dollop of the yogurt mixture.
