Chilled Summer Squash Soup with Yogurt, Mint, and Sourdough Croutons

Ingredients

• For the soup:
• 3 tablespoons butter
• 1 medium bunch green onions, white and green parts, chopped
• 3 medium garlic cloves, chopped
• Kosher salt and freshly ground black pepper
• 3 pounds mixed summer squash, chopped into medium pieces
• About 3 cups water
• 1 cup plain yogurt, low fat or full fat
• 1/4 cup chopped fresh mint leaves plus additional, for serving
• For the croutons:
• Half a medium loaf of sourdough bread, cut into a 1/2" dice
• 1 tablespoon extra virgin olive oil
• 1/2 teaspoon dried herbs, such as herbes de provence, optional

Directions

1. Set an oven rack in the middle position and heat the oven to 375 degrees F. Melt the butter in a large heavy-bottomed saucepan or Dutch oven over medium heat. Stir in the green onions and garlic, then add salt and pepper to taste. Cook for about 5 minutes, stirring now and then, until they soften and release some moisture without taking on color.
2. Add the summer squash, then season again with salt and pepper to taste. Continue cooking, stirring occasionally, until the squash starts to soften and give off moisture but does not brown, about 7-10 minutes. Pour in enough water to come just shy of covering the squash, about 3 cups. Set the lid slightly ajar, reduce the heat to medium-low, and simmer until the squash is barely tender, about 12 to 15 minutes.
3. As the soup simmers, make the croutons. Toss the bread cubes in a large bowl with the olive oil, salt and pepper to taste, and the dried herbs, if using. Spread them on a rimmed baking sheet and bake for 10 to 12 minutes, stirring occasionally, until deeply browned and crisp. Take them out of the oven and set them aside to cool.
4. Blend the soup with a hand blender until it is mostly smooth. If you are using a standard blender, work in two batches instead. Add the yogurt and mint, then blend until completely smooth, about 1 minute, again using batches if needed. If you want an extra-smooth soup, pass it through a fine mesh strainer.
5. Cool the soup at room temperature for one hour, stirring from time to time. Move it to the refrigerator and chill, with the occasional stir, until cold throughout, about 45 minutes. Taste and adjust with more salt, pepper, yogurt, or mint as needed. Ladle into bowls and finish with extra chopped mint and a handful of croutons.