Heat a dutch oven or large pot over med-high heat and add in olive oil, onion, garlic, leeks, and salt and pepper. Sauté for about 5 minutes.
Add white wine and simmer for another 2-5 minutes to reduce.
Add fish, tomatoes, potatoes, thyme, bayleaf, and chili powder.
Add enough water to cover everything.
Bring to boil, reduce and simmer the Greek fisherman's soup for 15-20 minutes.
One done, taste and adjust seasonings to preference.
Serve Greek fisherman's soup with some bread and enjoy!