In a large pot, saute the onions in the olive oil over medium heat until they are translucent, about 3 to 4 minutes. Add the garlic and saute 1 minute. Add the tomatoes, olives, bay leaves, and basil and allow to simmer for roughly 10 minutes. Add the chicken stock, baccala and potatoes; allow to simmer for another 10 to 15 minutes or until potatoes are tender. Season with salt and pepper, to taste and serve immediately.