What is your favourite burger recipe?

So, what is your favourite burger recipe?

An average home made burger pattie here involves:
mince
diced onion
garlic
worchestershire sauce
egg
rolled oats/breadcrumbs
tomato sauce/BBQ sauce/possibly sweet chilli sauce
(this time has periperi seasoning in and a bit of cajun seasoning, have used mixed herbs previously)

Mix up, let sit for a while, then fry up. Often works for two nights in a row, with the advantage that if you didn't quite get the mix right the first night, the remaining half that was refrigerated overnight can be adjusted the next night.

Bread works, buns can also work. Not fussed really. Often toasted.

Other things in burger:
cheese (grated or sliced and grilled on often nice)
sliced pineapple
lettice (if any around)
maybe sliced tomato
bbq sauce/tomato sauce

NOT:
beetroot

Your hamburger preferences/rules?