Regarding onions......

I sometimes cook a little diced onion in with the potatoes and carrots when I cook them. If not sometimes I use a dash of onion powder when I put it all together. Cabbage... I've never used but if it should be tender but not too mushy you might add it to the potatoes and carrots also. Just don't cook them too soft if you are going to have the soup cook for several hours. Don't rush it too much or the flavors don't blend enough. Also, be sure not to add the cooked noodles until just a little before serving or they turn to mush. I cook my noodles the night before also (hubby loves noodles in his) and store in cold water in the refrigerator. I love to make chili in the crockpot also then use the leftovers the next day for hot dogs and chili or a home version of frito chili pie, mmmmm.....