Melt butter or oil in a large pot over medium-high heat.

Cook the diced chicken until no longer pink.

Add the chopped onion, carrots, celery, and diced apple to the pot.

Stir well and cook gently for 5-6 minutes.

Add the curry powder and cook for a few more minutes, allowing the flavors to bloom.

Add the flour, mixing well to create a roux, and cook for a few minutes to brown slightly.

Add the tomato sauce and chicken broth.

Blend well to ensure a smooth consistency before bringing slowly to a boil.

Reduce the heat to low.

Add in the bay leaf, parsley, thyme, crushed red pepper flakes, and sugar.

Stir and simmer for 30-45 minutes with a lid on the pot.

Remove the bay leaf.

Add the lemon juice.

Stir in the cooked rice, or serve the soup over rice.

Season with salt and pepper to taste.

Serve hot and enjoy!