Unwrap the lamb and rub off any bits of tea. Add the lamb and cook over moderately high heat until browned all over, about 6 minutes. Press a tea-crumb square onto each piece of lamb and roast in the oven for 8 to 10 minutes, up until the crumbs are crisp and browned and the lamb is medium uncommon.
Reheat the sweet pea sauce and spoon it onto 4 plates. Slice the lamb, arrange on the sauce and serve at once.
The tea-crumb mix and the sweet pea sauce can be refrigerated over night.