If using olive oil, heat it over medium in a large non-stick soup pot. Otherwise, spray treat a large non-stick soup pot with cooking spray and heat over medium.
Saute the leeks for 2-3 minutes. Add the onions and garlic, and saute for another 3 minutes. Add the carrots and cook, stirring for another 3 minutes. Add the potatoes and green beans. Cook, stirring for 3 more minutes.
Add the tomatoes, wine, broth, and seasonings. Bring to a light boil, reduce heat, and simmer, covered for 20-30 minutes, until carrots and potatoes are softened to just tender.
Stir in the crabmeat, lemon juice, and then the tilapia. Stir once or twice, very gently. Cook for 7-10 minutes, until white fish is cooked through.
You can top this with parmesan cheese or crutons if desired.