Sauté onions until slightly caramelized. Keeping the heat high, add the poblano chilies; allow chiles to char slightly. Add garlic; being careful not to burn the garlic, stir 30 seconds.
Add chicken stock and tomatillos; leaving the pot uncovered, cook at a fast simmer for 45 minutes. As the tomatillos begin to break down, crush them with the back of your stirring spoon. Add spices and allow mixture to cool slightly. Adjust seasonings as needed.Makes 4