To cook silverside in a slow cooker:

1. Season the silverside with salt and black pepper.
2. Brown the silverside in a little oil in a frying pan or in the slow cooker on a high setting to seal in the juices and get a nice color.
3. Prepare vegetables like onions, carrots, and celery by slicing them thinly.
4. Place the vegetables in the base of the slow cooker.
5. Put the browned silverside on top of the vegetables.
6. Mix beef stock (or stock cube dissolved in water) with tomato puree and Worcestershire sauce, then pour this liquid into the slow cooker.
7. Cover and cook on low for 6 to 8 hours or on high for 4 to 5 hours, until the meat is tender and easily pierced with a fork.
8. After cooking, rest the meat for about 20 minutes before slicing.
9. Optionally, make gravy with the cooking liquid by thickening it with cornflour.

This method yields tender, juicy silverside perfect for a hearty meal with vegetables and sides like Yorkshire pudding or roast potatoes.