Step 1Place onions and garlic in the bowl of a slow cooker. Cut rump steak into large pieces. Season well with salt and pepper. Melt butter with oil in a large nonstick frypan over medium heat. Brown steak for 1-2 minutes each side, then transfer to a slow cooker. Whisk together French onion soup mix with 375ml boiling water. Stir through cream and Worcestershire sauce, then pour over steak and onions. Add thyme. Cook for 3-4 hours on high.Step 2Serve with potatoes or rice and steamed vegetables.