How to Make It
In a large skillet, heat 1 tablespoon of the oil until shimmering. Season the turkey legs with salt and pepper and add 3 of them to the skillet. Cook over moderate heat until richly browned, about 5 minutes per side. Transfer the turkey legs to a large slow cooker. Repeat with 1 tablespoon of the oil and the remaining 3 turkey legs.
Pour off the oil in the skillet. Heat the remaining 2 tablespoons of oil in the skillet. Add the garlic and onion and cook over moderately high heat, stirring often, until softened, about 4 minutes. Add the chicken stock and bring to a boil, scraping up any browned bits on the bottom of the skillet. Scrape the contents of the skillet into the slow cooker. Add the water, ancho chiles, fresh chiles and the cumin. Cover and cook on high heat for 3 hours, until the turkey is tender.
Transfer the turkey legs to a large rimmed baking sheet to cool slightly. With a slotted spoon, skim the chiles, onions and garlic from the broth; transfer to a blender and puree. Add the puree to the slow cooker and stir in the corn and lima beans. Cover and cook for 1 hour, until the lima beans are tender.
Meanwhile, remove the meat from the turkey legs and tear it into bite-size pieces. Discard the skin, bones and tendons. In a small heatproof bowl, blend the butter with the flour to form a paste. Gradually whisk in 1 cup of the hot broth. Whisk the mixture into the soup and add the turkey. Cover and cook, whisking a few times, until the broth is thickened, about 15 minutes. Season with salt and pepper. Serve with tortilla chips.