Combine com, cabbage, onions, green and red pepper in a large kettle.
Mix together mustard, flour and turmeric. Add ¼c. vinegar to mustard mixture; stir to blend well. Add mustard mixture, remaining vinegar, sugar and salt to vegetables, mixing well.
Bring vegetables to a boil; reduce heat and simmer, uncovered, 15 minutes. Ladle into hot jars; adjust lids. Process in boiling water bath (212°) 15 minutes. Remove jars and complete seals unless closures are self-sealing type.