Put the butter and onion in a saucepan, shake it over the fire, then add the cold boiled lamb, cut into blocks; you should have one pint. When this is boiling add all the seasoning and stand the mixture over hot water on the back of the stove while you make the canapés. Press the peas through a sieve; the pulp must be quite dry; add to it a palatable seasoning of salt and pepper and one or two tablespoonfuls of melted butter. Put these in a pastry bag. Toast the bread on one side, put the peas around in rope-like form, or roses, on the untoasted side, making a border sufficiently high to hold the lamb. Stand in the oven until the bread is carefully toasted. Arrange them on lace papers on heated plates, fill the center with the lamb mixture and send to the table.