Place the beans in a large bowl or pot and cover with water by 2 inches. Let soak for 8 hours or overnight. Drain and set aside.
In a large pot, heat the bacon grease over medium-high heat. Add the tasso and sausage and cook, stirring, until cooked through and the fat is rendered, about 5 minutes. Remove with a slotted spoon and drain on paper towels.
Add the onions and bell peppers to the fat remaining in the pot. Season with the pepper and cayenne and cook, stirring, until the vegetables are soft, about 4 minutes. Add the bay leaves, parsley, thyme, and ham hock, and cook, stirring, to brown the ham hock, 4 minutes. Add the garlic and cook for 1 minute. Add the beans and enough stock or water to cover by 1 1/2 inches, stir well, and bring to a boil. Return the tasso and sausage to the pot. Reduce the heat to medium-low and simmer, uncovered, stirring occasionally, until the beans are tender and starting to thicken, 1 1/2 to 2 hours. (Should the beans become too thick and dry, add more stock or water, about 1/4 cup at a time.)
Remove from the heat and with the back of a heavy spoon, mash about 1/4 of the beans against the side of the pot. Continue to cook until the beans are tender and creamy, 15 to 30 minutes. Remove from the heat and remove the bay leaves. Cover to keep warm until ready to serve.
Yield: 4 servings