In a large frying pan fry the chopped onion in the butter and oil until transparent. Add the peas and water enough to cover, and add salt and pepper.
Make a cut of about 2 ins. (5 cms) into each end of the frankfurters and add them to the peas when the water has just about evaporated. (After about 30 mins cooking time.) Continue cooking for another 5 mins approx.