Over medium-high heat, in a large saucepan, warm 2 tbsp. oil. Add curry powder and cinnamon. Heat for 30 seconds, stirring occasionally.

Add onions and saute until tender, 5-6 minutes.

Transfer contents of pan, including the oil and seasonings, to a blender. Add mango and 1 cup of broth. Puree until smooth.

Put last tbsp. oil in saucepan and heat over medium-high heat. Add chicken and saute until cooked through and browned, 6-8 minutes. Add remaining broth. Stir contents of pan thoroughly and bring to a simmer.

Stir mango puree into saucepan and re-heat to simmer. Stir in sour cream and lime juice. Stir in salt and pepper.

Remove from heat and serve, garnishing each serving with fresh cilantro and extra sour cream, if desired.