In a large pot, saute onions in oil until golden brown. Add garlic, tomatoes, beans and 0.5 l water and simmer covered until they are very tender (this can take 4-5 hours). Stir every now and then to make sure they don't get stuck at the bottom. If neccesary, add more water.

Once the beans are very tender, add the stock cube disolved in a little water and the peanut butter and cook for another hour. You should end up with a very thick sauce, if required, add extra water. Serve over rice. Goes well with chicken curry and Chapaties.

Instead of peanut butter you can also use 2 cups of coconut milk.