Heather's Chicken Key Lime Curry

This recipe is the one of the curry we made when Jessie, Dave and I came to Mississippi for Spring Break from our freshmen year.

2 large onions, sliced (4 cups), divided
1 (1-inch) piece peeled ginger, chopped
4 garlic cloves
2 1/2 cups water, divided
2 tablespoons vegetable oil
1 chicken (about 3 1/2 pounds), cut into serving pieces
2 tablespoons curry powder (preferably Madras)
2 tablespoons tomato paste
1 tablespoon sugar
1 Key lime, thinly sliced

2 tablespoons fresh Key lime juice Blend 1 cup onions with ginger, garlic, and 1/2 cup water in a blender. Heat oil in a 12- to 14-inch heavy skillet over medium-high heat until it shimmers. Pat chicken dry and season with 1 teaspoon salt and 1/2 teaspoon pepper. Brown, skin side down, about 6 minutes (don’t turn over), then transfer to a plate. Add remaining onions to skillet and cook, stirring occasionally, until softened and browned, 8 to 10 minutes. Transfer with a slotted spoon to plate with chicken. Reduce heat to medium and add onion-ginger paste to skillet. Cook, stirring, 1 minute. Add curry powder and cook, stirring, 1 minute. Stir in tomato paste, remaining 2 cups water, sugar, and 1/2 teaspoon salt and bring to a simmer. Return chicken and onions to skillet with sliced lime and simmer, partially covered, turning chicken once, until just cooked through, 25 to 30 minutes.