Over medium-high heat, melt the butter in a large heavy saucepan.
Add turtle meat and garlic. Cook until the meat is no longer pink, about 5 minutes, stirring occasionally.
Stir in onions, celery, bell peppers, kosher salt, and pepper.
Cook until the vegetables start to become translucent, about 10 minutes.
Add tomatoes and cook about 5 minutes, stirring often so the bottom of the pan does not scorch.
Reduce the heat to medium.

Dust the vegetables with flour and cook 5 minutes, stirring constantly and scraping the pan bottom clean so the flour does not burn.
Slowly add the stock, stirring and scraping the pan bottom constantly to prevent dough balls from forming in the soup.
Stir in the Worcestershire, pepper sauce, parsley, and thyme. Simmer 30 minutes.
Add the eggs, spinach, lemon zest, lemon juice, and sherry.
Continue simmering 10 minutes more.
Serve warm in heated cups or bowls.