Heat 1 teaspoon oil in a Dutch oven over medium-high heat. Add chicken; stir-fry 12 minutes or until golden. Remove chicken from pan; set aside.
Heat 1 teaspoon oil in pan. Add celery, onion, and garlic; sauté 3 minutes or until tender. Stir in curry powder, peppers, and salt; cook 1 minute. Stir in the water, coconut, broth, and tomatoes. Return chicken to pan; bring to a boil. Cover, reduce heat, and simmer 30 minutes. Stir in banana; simmer 10 minutes or until thoroughly heated.