Homemade Vegetable Soup

In a large pot over medium heat, heat oil and butter until butter melts. Add basil, thyme, and red pepper (if using). Cook, stirring frequently, until bloomed and fragrant, about 30 seconds. Add onion, grated garlic, and 2 teaspoons salt. Cook, stirring occasionally and reducing heat to medium-low if onions begin to color too quickly, until onions start to soften and begin to turn lightly golden, about 6 minutes.

Add tomatoes and bouillon and cook, using the back of the spoon to gently mash, until tomatoes are softened and incorporated into onion mixture, 2 to 3 minutes.

Add carrots, celery, potatoes, and fennel; season with 1 teaspoon salt. Cook, stirring occasionally, until heated through, about 1 minute. Add Parmesan rind, sliced garlic, and 8 cups water. Bring to a gentle simmer, then reduce heat to medium-low. Cook, stirring occasionally, until vegetables are tender, 20 to 25 minutes.

Remove Parmesan rind. Stir in corn, green beans, peas, and parsley until vegetables are thawed; season with salt, if needed.