Warm the pot: Heat the olive oil in a large soup pot over medium heat. When it shimmers, add the onion, carrots, and celery with a pinch of salt. Cook 5–6 minutes, stirring occasionally, until the vegetables are soft and fragrant.
Build the base: Stir in the garlic, tomato paste, Italian seasoning, and cumin.
Cook 1 minute until the tomato paste darkens slightly. This step adds depth without extra fat.
Add the core veggies: Add potatoes, zucchini, green beans, and bell pepper. Toss to coat in the aromatic base for 1–2 minutes.
Simmer: Pour in the diced tomatoes with their juices and the broth.
Add the bay leaf. Bring to a gentle boil, then reduce to a lively simmer. Cook 15–18 minutes, or until the potatoes are tender but not falling apart.
Finish with greens: Stir in the chopped spinach or kale and cook 2–3 minutes, just until wilted and bright.
Season smartly: Remove the bay leaf.
Add lemon juice, then taste and season with salt, black pepper, and red pepper flakes if you like. Adjust acidity and salt—small tweaks make a big difference.
Serve: Ladle into bowls and garnish with fresh parsley or basil. If desired, add an extra squeeze of lemon for brightness.