If you are using peanuts, use less meat - so that you have equal amounts of peanuts and meat.
Shell the peanuts, roast them on a baking sheet in a hot oven, or in a large skillet on the stove, stirring often, and then remove the skins.
Place the peanuts in a saucepan, add enough water to partially cover them and bring to a slow boil, stirring often.
Reduce heat. Crush peanuts with a potato-masher.
Simmer for 15 minutes, then add meat and continue to simmer until all the water is evaporated (30 minutes or so).
Warm the banana leaves for a half-minute in a hot oven, or on a grill, or in a pot of boiling water. This makes them easier to fold.
Remove the centre rib of each leaf by cutting across it with a knife and pulling it off.
Cut the ends off each leaf to form a large rectangle
Sprinkle salt and pepper directly on to the banana leaves.
Place the meat (or meat and peanut mixture), onions, and chilli pepper on the banana leaves.
Moisten the meat with lemon juice and water (skip the lemon juice if using peanuts).
Fold the banana leaves to completely enclose the ingredients in a packet two or three layers thick. (Use something like the burrito folding technique. Depending on how many leaves you have you may want to make more than one packet. You can use oven-proof string to tie them closed.)
Steam the packets by placing them on a rack over boiling water in a large covered pot, or cook them on an outdoor grill or in an oven. (If using an oven, you may want to place some aluminium foil under them to catch drips.)
Turn them every 10 minutes.
After about an hour, carefully open the packet and check the meat. If it is not done, close the packet and continue cooking.