Season the ribs on both sides generously with the salt and pepper. Rub the grated garlic and jalapeno peppers onto the ribs (both sides) and layer the sliced peppers and onions on top of the ribs.
Wrap the ribs in foil (it is best to wrap each slab individually) and place in the refrigerator and marinate for 24 - 48 hours.
When ready to bake pre-heat oven to 275 degrees. Place the ribs, still wrapped in foil, on a heavy baking sheet. Leaving the ribs wrapped will keep the steam in and make them tender. Make sure not to place the ribs on the lower rack of oven and bake for 8 hours. The meat should easily pull away from the bone.