1-Start with a nice fire that will give you a nice bed of coals
2-Cut up some pieces of foil big enough to wrap your fillets
3-In the middle of the foil spread some butter the size of your fillet
4-Place a fillet skin off, back against the butter
5-In a bowl mix some diced tomatoes, lemon juice, chopped onin and season to your taste buds
6-Place a nice layer of the mixer on the fillet
7-Wrap your fillet with the foil and double your foil. (Don't be affraid of using lots of foil, I usually have 4 layers of foil per side)
8-Once your fire becomes a bed of coals trow in the packs and flip after 15 minutes, cook for an other 15 minutes.
9-ENJOY!!
Hope this help, P.S. no dishes to wash