Note: We use alligator snapping turtles, a farm-raised, fresh-water species available all year. Turtle meat usually comes in 2 1/2-pound portions, so this recipe is written to use that quantity. Although it's illegal to use sea-raised turtle, farm-raised is fine. It freezes well and can be ordered by mail.
Melt 4 tablespoons of butter in a large soup pot over medium to high heat. Brown the meat in the hot butter, season with salt and pepper, and cook for about 18 to 20 minutes, or until liquid is almost evaporated. Add the onions, celery, garlic, and peppers, stirring constantly, then add the thyme, oregano, and bay leaves, and saute for 20 to 25 minutes, until the vegetables have caramelized. Add the stock, bring to a boil, lower the heat, and simmer uncovered for 30 minutes, periodically skimming away any fat that comes to the top.
While the stock is simmering, make a roux in a separate pot: Melt the remaining 8 tablespoons of butter over medium heat in a small saucepan and add the flour a little at a time, stirring constantly with a wooden spoon. Be careful not to burn the roux. After all the flour has been added, cook for about 3 minutes until the roux smells nutty, is pale in color, and has the consistency of wet sand. Set aside until the soup is ready.
Using a whisk, vigorously stir the roux into the soup a little at a time to prevent lumping. Simmer for about 25 minutes. Stir to prevent sticking on the bottom.
Add the Sherry, bring to a boil, add the hot sauce and the Worcestershire, and simmer, skimming any fat or foam that comes to the top. Add the lemon juice and tomatoes, and return to a simmer. Add the spinach and the chopped egg, bring to a simmer, and adjust salt and pepper as needed. This soup freezes well.