Curry Sauce

Peel and slice six large onions, put them into a covered stewpan, with two ounces of butter, over a slow fire to stew, without acquiring any colour; then add three apples sliced, without peeling them; and having replaced the whole on the fire again, as soon as these are also dissolved, add a good tablespoonful of Captain White's curry paste; moisten with a pint of good gravy, and having stirred the sauce over the fire for twenty minutes, rub it through a hair sieve or tammy, and put it into a small stewpan, to be used as will be hereafter indicated.