Slice three of the onions and set aside. Cut the remaining two onions into chunks.
Process the chunked onions with chile peppers, ginger, and garlic until pureed.
Mix together salt and turmeric, then rub the chicken pieces with this mixture.
Heat oil in a large skillet over medium-high heat. Add chicken and cook until browned on both sides, about 10 minutes total. Remove chicken and set aside.
Add sliced onions and pureed onion mixture to the pan. Cook, stirring occasionally, until sliced onions are very limp.
Process canned tomatoes with their liquid until smooth. Add to skillet along with water, soy sauce, and lemon zest.
Return chicken pieces to pan except for breast pieces. Cover and simmer for 25 minutes.
Add breast pieces and continue simmering covered for 20 more minutes, or until meat is no longer pink.
Remove chicken to serving dish and cover to keep warm.
Boil sauce uncovered, stirring constantly, until reduced to about 3 cups. Skim off fat and spoon sauce over chicken.