2 tsp olive oil
1 small red onion, chopped
1 medium zucchini, trimmed and diced
3 large mushrooms, chopped
1 head of escarole, trimmed, well rinsed, and chopped
1 tsp dried oregano
1/2 tsp mild red pepper flakes, or more or less to taste
Leaves from 10 sprigs of fresh thyme
8 cups chicken stock, homemade or store-bought low sodium
1 cup diced cooked chicken breast (I use rotisserie chicken), optional
1 cup dried cheese or spinach tortellini
1 Parmigiano-Reggiano cheese rind
Kosher salt and fresh black pepper, to taste
In a Dutch oven or heavy stock pot, heat the oil over medium heat. Sauté the onion until it is translucent, 1-2 miutes. Add the zucchini and mushrooms, and cook, stirring occasionally, for 2-3 minutes, until the zucchini is softened but not yet starting to brown. Add the chopped escarole, oregano, red pepper flakes, and thyme leaves. Stir everything together, and cook for 2 minutes until the escarole is wilted.
Pour in the chicken stock, raise the heat to high, and bring the soup to a boil. Reduce heat to simmer, cover, and cook for 10 minutes, stirring once or twice. Add the remaining ingredients, and continue to cook, uncovered, for 10 minutes or until the tortellini are soft. Adjust seasoning with salt and pepper, if needed. Serve hot.