Pat chicken dry. Heat smaller amount of oil in heavy large skillet or Dutch oven over medium high heat. Add chicken in batches and cook on all sides just until no longer pink (do not brown). Remove using slotted spoon and set aside. Heat remaining oil in skillet. Add sliced onion and fry until wilted and pale brown, stirring constantly to color evenly, about 12 minutes. Stir in almonds, coriander, ginger, cardamom, ground red pepper, cumin and fennel and cook 3 to 5 more minutes. Remove mixture from heat. Transfer half of mixture to processor or blender. Puree with 1/2 of the yogurt and 1/2 of the water. Repeat with the rest of the mixture, yogurt and water. Pour sauce back into skillet. Add chicken to skillet. Place over medium high head and bring to a boil. Reduce heat, cover and simmer until chicken is tender and sauce is thickened, about 45 minutes. Remove from head. Let stand at room temperature for 30 minutes (dish is best refrigerated and reheated). Rewarm over low heat. Transfer to serving dish, garnish and serve immediately.