During my marathon training, I played around with a few simple foods to eat the day before a long run/the big day. I stuck pretty closely to the following:
Barley Protein Bowl
Half a can of water-packed tuna
Chopped fresh spinach
Half an avocado
Salt & Pepper
All of this mixed up and warmed! Served with boiled sweet potatoes sprinkled with ginger powder and raw honey, with a glass of water mixed with some tart cherry juice and apple cider vinegar.