In the same large deep skillet cook, onion, garlic, coriander & pepper in margarine til onion is tender. Stir flour into sour cream using a whisk. Slowly add small amounts to onion mixture while stirring with whisk. Stir in broth & chili's all at once. Cook & stir til thickened & bubbly. Remove from heat; stir in 1/2 C of the cheese. Let cool slightly for handling.