Put the mince into a bowl. Add the garlic, onion, marjoram, sun-dried tomatoes and onion, then season with salt and black pepper.
Combine the mixture well, then rest in the fridge until needed.
Take the mixture out of the fridge and mix in the fresh herbs.
Divide the mixture into 4-6 equal portions. Shape these into balls.
Using your fingers make a well in each patty and add a small lump of the gorgonzola, then cover up with the mince mixture.
Flatten them between your palms.
Heat a griddle pan or frying pan. Lightly brush both sides of the patties with some oil. Cook them for 4-5 minutes on each side, depending on how well cooked you like your beef. You can cover them with thin slices of gorgonzola, if you like - although this will spoil the surprise!
Cut the buns in half and toast them. Assemble the burger to your liking then serve immediately.