Pre-heat the oven to 400 degrees. Heat the olive oil in a 12-inch ovenproof non-stick skillet over medium heat. Add the potatoes slices and cook for about 8-10 minutes, stirring occasionally until the potatoes are light brown and a little crispy. Add the bell pepper and asparagus and cook for another 5-8 minutes, stirring occasionally until the asparagus is cooked through but still crunchy. Add the kale and cook for about 1 minute until it wilts.