Place cookie sheet in oven. Heat oven to 200ºF. In 12-inch nonstick skillet, heat oil over medium heat until hot. Cook onion in oil about 5 minutes or until translucent. Add bell pepper; cook about 5 minutes or until softened. Add kale; cook about 5 minutes or until wilted. Add water and salt; cook 5 minutes, stirring frequently. Set aside.