VEGGIES: Add the 3 tablespoons olive oil to a large cast iron pot. Heat to medium and once oil is hot, add the 1 cup diced carrots, 1 cup diced celery, 1 cup diced onion, and heaping 1 tablespoon minced garlic. Add a tiny pinch of salt and cook, stirring often, until veggies are tender, about 7-9 minutes. Add in the tomato paste and stir for another 1 minute. Add in the 1/2 teaspoon dried thyme, 1/2 teaspoon dried oregano, 1/2 teaspoon salt, 1/2 teaspoon cracked pepper, and 1 teaspoon Italian seasoning. Cook and stir until fragrant, about another 30 seconds.
SIMMER: Add both cans of undrained, fire-roasted diced tomatoes and 6 cups vegetable stock. Add the 2 bay leaves and bring the soup to a boil. Once boiling, reduce the heat to low and simmer for 10 minutes, covered most of the way with a lid (leave a 1 inch gap for the steam to escape).
QUINOA: Remove the lid entirely and add in the rinsed quinoa. Cook, uncovered, for 15 minutes over low heat (soup should be maintaining a simmer, but not boiling).
REST OF THE VEGGIES: After 15 minutes, add in the 1 can of drained and rinsed white beans, 1 cup frozen corn, 1/2 cup frozen beans and 1/2 cup diced zucchini. Stir and cook for 5 more minutes or until quinoa has fully "popped" and the veggies are warmed through. Remove from heat and gently stir in the spinach. The spinach should wilt within a minute or two. Finish the soup with 1 more tablespoon olive oil and 1 more tablespoon lemon juice. Taste and adjust seasonings as needed. Remove the bay leaves and serve.
SERVE: Garnish bowls of soup with grated Parmesan cheese and chopped fresh parsley, if desired.
STORAGE: Soup will continue to thicken as the quinoa expands. We still think it tastes great, but it does get thicker and thicker as it stands. This soup is best eaten within 2-3 days. It does not freeze well; the soup continues to absorb liquid and gets overly bloated.
SLOW COOKER INSTRUCTIONS: Follow step one and then transfer everything from that pot to a 6 quart crockpot. Add in the diced tomatoes, stock, rinsed quinoa, drained and rinsed white beans, zucchini, frozen corn, frozen peas, and bay leaves. Cook on high for 2-3 hours or low for 3-5 hours or until quinoa has popped and veggies are tender. Stir in spinach, olive oil, and lemon juice. Remove bay leaves. Adjust salt and pepper; serve in bowls garnished with fresh parsley and topped with Parmesan cheese.