Step 1

First, make the sauce: Combine tahini, lemon juice, garlic, salt, cumin and red-pepper flakes with 2 tablespoons water in a medium bowl. Whisk until smooth, adding more water as needed to achieve a drizzle-able consistency, and set aside.

Step 2

Next, make the soup: Add stock to a Dutch oven or heavy pot, and bring to a boil over high heat. Stir in spinach, cilantro, tahini and salt, and return to a boil. Turn off heat, and stir in lemon juice.

Step 3

Use an immersion blender to purée soup. Taste, and adjust seasoning with more salt and lemon, if desired.

Step 4

Serve soup immediately, and drizzle with tahini sauce. Cover and refrigerate remaining soup and sauce for up to 1 week, or freeze soup for up to 1 month.