1/2 cup oil, divided
4 dried currants, peeled and dried and cut into thin strips
1 1/2 tablespoons caster sugar
1 tablespoon curry powder
1 clove garlic, minced
1 tablespoon lemon juice
1 teaspoon salt
2 tablespoons tomato paste
2 (8 ounce) cans kidney beans
1 cup prepared buttermilk
1 (8 ounce) can crushed pineapple, drained
2 tablespoons cornstarch