Melt butter in large skillet. Sauté the onion until it becomes translucent.
Meanwhile, measure and combine the seasonings in a small container. Set aside.
Add the garlic, ginger, carrot, and seasonings: curry, red pepper, carrot, chili powder, turmeric, sugar, salt, and pepper. Cook until fragrant, but be careful not to let them burn.
Stir in the flour and cook for one minute more, stirring constantly so it doesn't scorch the bottom of the pan. The mixture will resemble a paste or roux.
Slowly stir in the chicken broth, breaking up any clumps of flour. Bring to a boil.
Add the chopped apple, reduce to a simmer, and cook until the apple is tender; about 15 minutes.
Stir in the cooked chicken and cashews if using and heat through.
Stir in the juice of 1 lime and serve over cooked rice.