Step 1

Heat the oil in a Dutch oven over medium heat until shimmering. Add the onion, celery, carrot, garlic, salt, and pepper. Cook, stirring occasionally, until tender, about 6 minutes.

Step 2

Meanwhile, finely grate the zest 1 of the lemons and set aside. Juice both lemons until you have 1/4 cup of juice; set aside.

Step 3

Stir the lemon zest into the soup and cook for 1 minute. Add the broth and tortellini and bring to a boil. Reduce the heat to maintain a simmer and simmer until the tortellini is cooked through, 5 to 6 minutes (less if using fresh tortellini — check at 3 minutes). Stir in the spinach and 1/4 cup lemon juice, and cook until wilted, about 1 minute.