Heat olive oil in a large stock pot over medium-high heat.Add onions, leeks, carrots, and celery and saute 4 minutes then add garlic, thyme, chili flakes and tomatoes and saute until the tomatoes start to break down - another 4-5 minutes.Add in broth, potatoes, bay leaves, and season with salt and pepper to taste. Bring to a boil, then add green beans.Reduce heat to medium-low, cover and simmer until potatoes are almost fully tender, about 20 - 30 minutes.Add corn and cook 5 minutes longer. Stir in the parsley and lemon juice and ladle into bowls and serve immediately with crusty bread.Leftover vegetable soup will keep on a sealed container for 3 to 4 days in the refrigerator.