In a saucepan combine oil, poblano peppers, onions, garlic and Southwest seasoning; season to taste with salt and pepper. Saute over high heat, stirring occasionally, 2 minutes. Stir in stock, bring to a boil, and boil vigorously, 18 minutes. Reduce heat to medium, stir in heavy cream, and simmer 2 minutes. Transfer sauce to blender or food processor and puree until smooth.
Yield: 2 cups