In large saucepan melt fat over medium-high heat. Saute onion until golden brown, about 10 minutes. Add garlic and cook briefly, just until aroma is released. Add chicken stock, hominy and carnitas. Reduce heat and simmer, uncovered, about 10 minutes. Add tomatillo salsa and bring to a boil Reduce to a simmer and cook and additional five minutes. Season to taste with salt and pepper.