Place flour in a large Ziploc bag.
Add steaks, a few at a time, and shake until completely coated.
In a skillet, cook steaks in oil until lightly browned on each side.
Transfer steaks to crock pot.
Add onion and 2 cups water.
Cover and cook on low for 8 hours or until meat is tender.
In a bowl, whisk together gravy mixes and remaining 1 cup water.
Add to crock pot, and cook for 30 minutes longer.
Serve over mashed potatoes.