- 2tablespoons olive oil, plus more for the grill pan
- 2 large onions, chopped
- 4 cloves garlic, chopped
- 1 28-ounce can whole peeled tomatoes
- 3 1/2cups low-sodium chicken broth
- 1teaspoon dried thyme
- kosher salt and black pepper
- 1/2cup sour cream
- 2tablespoons prepared horseradish
- 8slices sandwich bread
- 8ounces thinly sliced roast beef
- 8ounces sharp white Cheddar, sliced
- 2cups baby arugula (1 1/2 ounces)
- Heat the oil in a large saucepan over medium-high heat. Add the onions and garlic and cook, stirring often, until softened, 5 to 7 minutes. Add the tomatoes (with their juices), broth, thyme, and ½ teaspoon each salt and pepper. Simmer, stirring occasionally, until slightly thickened, 15 to 20 minutes. Working in batches, in a blender, puree the mixture until smooth.
- Meanwhile, in a small bowl, stir together the sour cream and horseradish. Form sandwiches with the bread, roast beef, Cheddar, arugula, and half the horseradish mixture. Heat a lightly oiled grill pan over medium heat and cook the sandwiches until the cheese is melted, 5 to 6 minutes per side. Top the soup with the remaining horseradish mixture and serve with the sandwiches.