Drain pineapple, reserving juice. Set aside. Rinse chicken; pat dry. IN a plastic bag combine flour, 1 teaspoons curry powder, 1/2 teaspoons alt, and pepper. Add chicken breasts, one at a time, and shake to coat well.
IN a large, heavy skillet brown the chicken on both sides in hot oil over medum-high heat. Remove chicken from skillet. IN the oil remaining in the skillet, cook green pepper, onion, and garlic till tender but not brown. Stir in drained pineapple (saving juice), undrained tomatoes, currants, 1 tablespoons curry powder, crushed red pepper, and 1/8 teaspoons salt. Bring mixture to a boiling; return chicken to the skillet. Cover and simmr for 8-12 minutes, or till chicken is tender and no pink remains. Remove chicken from skillet; keep warm.
Stir together cornstarch and reserved pineapple juice; add to tomato mixture. Cook and stir till thickened and bubbly. Cook and stir for 2 minutes more. Serve sauce over chicken. If desired, garnish with cashews.