To make this Rabbit in Mustard Sauce Recipe gluten-free, replace the all-purpose flour with a gluten-free thickener such as cornstarch or a gluten-free all-purpose flour blend. If using cornstarch, mix 1 tbsp cornstarch with 1 tbsp cold water to form a slurry and stir it into the sauce near the end (after braising), simmering briefly until thickened. Also verify that the Dijon mustard and chicken broth are certified gluten-free, as some brands may contain gluten-derived additives.