To make sure that this dish is free of gluten it's important to select a brand of cornstarch that has been certified as gluten. Cornstarch does not naturally contain gluten, which makes it a great option, for thickening your Slow Cooker Ham, Potatoes and Green Beans recipe. Remember to read the labels of any packaged ingredients to ensure they are also gluten-free. Enjoy your meal without any gluten concerns. Savor the flavors.