Why It Works
- Leeks are a mild onion that complement mild zucchini perfectly.
- Adding basil in two stages gives you layers of basil flavor.
The great thing about this zucchini-basil soup is that it cooks so darn quickly. Zucchini is a very watery vegetable, with a weak, almost spongy structure that breaks down rapidly during cooking. This is frequently an obstacle when you're preparing zucchini, but here, it's a positive: It means we can cook the zucchini until it's tender enough to blend, while retaining its bright green color for a soup that's both tasty and attractive.
- 2 tablespoons (30ml) extra-virgin olive oil, plus more as needed and to serve
- 1 large leek, finely diced (about 8 ounces; 225g)
- 3 medium ribs celery, finely diced (about 6 ounces; 170g)
- Kosher salt
- 3 medium cloves garlic, minced (about 3/4 ounce; 25g)
- 1 1/2 pounds (700g) zucchini, split lengthwise and cut into 1/2-inch disks (see note)
- 2 cups packed fresh basil leaves, roughly chopped (about 2 ounces; 55g), divided
- 5 cups (1.2L) water
- Freshly ground black pepper
- Fresh juice from 1 lemon, to taste
Heat olive oil in a large saucepan or saucier over medium heat until shimmering. Add leek and celery. Season with salt and cook, stirring, until vegetables are softened but not browned, about 5 minutes. If pan starts to look dry at any point, add a small splash of olive oil. Add garlic and cook, stirring, until fragrant, about 30 seconds. Add zucchini and cook, stirring, for 1 minute. Add half of basil, stir to combine, and add water.
Bring to a simmer and cook, stirring occasionally, until zucchini is tender but still bright green, about 10 minutes. Add remaining half of basil and blend soup using a handheld immersion blender or a countertop blender until it is as rough or as smooth as you like it. Season to taste with salt, black pepper, and lemon juice and serve, drizzling with additional olive oil at the table.
Immersion blender or countertop blender
Use young, firm zucchini for this recipe; larger zucchini will be more watery. The soup can be served hot, but is also delicious chilled on a hot day.