A melange of navy beans or pea beans (the latter a favorite with New Englanders), salt pork, molasses and brown sugar, baked in a casserole for hours until tender. The dish is so named because it was made by Puritan Bostonian women on Saturday, to be served for dinner that night. Because cooking was forbidden on the Sabbath, leftover beans were served with boston brown bread for Sunday breakfast . . . and, ofttimes, lunch.