Super Greens Soup with Lemon-Tarragon Cream | America's Test Kitchen

Ingredients

• 1/4 cup heavy cream
• 3 tablespoons sour cream
• 1/2 teaspoon plus 2 tablespoons extra-virgin olive oil
• 1/4 teaspoon finely grated lemon zest plus 1/2 teaspoon juice
• 1/2 teaspoon minced fresh tarragon
• Salt and pepper
• 1 onion , halved through root end and sliced thin
• 3/4 teaspoon light brown sugar
• 3 ounces white mushrooms , trimmed and sliced thin
• 2 garlic cloves , minced
• Pinch cayenne pepper
• 3 cups water
• 3 cups vegetable broth
• 1/3 cup Arborio rice
• 12 ounces Swiss chard , stemmed and chopped coarse
• 9 ounces kale , stemmed and chopped coarse
• 1/4 cup fresh parsley leaves
• 2 ounces (2 cups) baby arugula