Heat the griddle and a small pan. Place onions, tomatoes on one side of the table; then pate, lettuce and buns on the other side.
Get your kid to peel the lettuce layer by layer, asking him or her to try and tear the lettuce close to the size of the buns.
While your kid is busy, you can slice your onions and tomatoes.
Place some butter into the pan and stir-fry onions till golden brown, place them and the tomatoes onto a large plate.
Ask your kid to butter the inner sides of the bun, place the patties on to the oiled griddle.
Depending on the thickness of your patties (mine were about 2cm thick), 4-5 minutes for well cooked. Keep flipping to prevent burning.
When your patties are almost done, place the butter buns on the griddle for that crisp. Give your kid a mini ice-cream scoop and let him make little balls of duck pate to place of the plate.
Arrange all of your ingredients nicely, and you're done! Your guests will now have some fun creating their own burgers. The pate will add some nice flavour when you spread them on to the beef patty. Sliced cheese is optional.
Tomatoes are a lot easier to slice if you first make little cuts on the surface according to desired thickness, THEN slice through each of them. If you do not have a mini ice-cream scoop, a tbsp measuring spoon will be a good size, but you'll have to dip your spoon in melted butter in order for the pate to fall out nicely. I used chopped onion which you can buy straight from waitrose ;) Saves time and washing up!