In a large pot over medium heat, warm the olive oil until shimmering, then add chopped onion. Sauté for about 5 minutes until translucent and lightly golden.

Stir in minced garlic, diced carrots, and chopped celery. Cook for 3 to 4 minutes, stirring occasionally, until vegetables begin to soften and garlic releases its fragrant warmth.

Sprinkle in salt, black pepper, and red pepper flakes. Stir well to coat. Cook for another minute until spices bloom and veggies become even more colorful.

Pour in vegetable broth, then tuck in bay leaves and thyme sprigs. Increase heat to medium-high, bringing the mixture to a gentle boil.

Add cubed potatoes, reduce heat to low, and cover. Let simmer for 10 minutes until potatoes are just tender when pierced with a fork.

Stir in zucchini, green beans, and tomatoes. Cook uncovered for 5 to 7 minutes until all vegetables are tender-crisp and colors remain vibrant.

Remove bay leaves and thyme sprigs. Taste and adjust seasoning if needed, adding extra salt or pepper for balance.

Ladle soup into bowls, drizzle with a squeeze of fresh lemon juice, and garnish with chopped parsley for a bright, fresh finish.