Mix 3/4 c water, brown sugar, vinegar and soya sauce in crock pot or sauce pot. Simmer ribs in sauce for 1 1/2 hours or crock on low for 6-8 hours or on high for 4-5 hours.
Mix cornstarch, 3 T water and ketchup. Add to ribs and simmer 20 minutes more or add to crock for last hour of cooking.