A 5 day fast is too short for potassium deficiency, so no real worries about eating anything in particular. I often eat very large meals to break a medium fast, however, to be safe, a small meal first and then meat a bit later is a prudent choice. But just an fyi, I have broken a 5 day fast with a one pound ribeye without issues. Anything longer than 5 days I usually do bone broth, and then a larger meal a bit later.