3lb. beef bottom roast, trimmed of visible fat
1 medium sweet onion, thinly sliced
1-11oz. jar pepperoncini sliced, and 1/2c. pepperoncini juice reserved
1/2c. olive oil
1/2c. water
1-.7 pouch Italian Vinaigrette Salad Dressing Mix
1tb. minced garlic
Ciabatta or Sourdough rolls
Arugula and sliced tomatoes to top sandwich
Place beef and onion in a 3 1/2-qt or larger slow cooker. Mix pepperoncini juice, oil, water, dressing mix and garlic in a small bowl until blended. Pour over beef. (If you have time, cover the crock and place in refrigerator to let beef marinate the night before, turning occasionally.)
Cover and cook on low 8 to 10 hours until beef is tender.
Cut rolls lengthwise in half (lightly toast if desired) and brush cut sides with some of the cooking liquids. Pour remaining liquid into a serving bowl.
Transfere beef to cutting board; let rest 15 minutes, then slice thinly. Layer beef, onions, sliced pepperoncini, tomatoes, and arugula on bottom half of rolls. Cover with top. Serve with reserved cooking liquid for dipping.