Soak the Dried Porcini Mushroom (20 gram) in hot water for 15 minutes. Then strain. Finely chop the Cremini Mushroom (200 gram) and porcini. (You can also just use a food processor for convenience).
Heat the Butter (1 tablespoon) in a pan over a moderate-high heat and fry the mushrooms with some Salt and Pepper (to taste) for 5-7 mins. Remove from heat and allow to cool.
Add the cooked mushrooms to the Butter (7 tablespoon) along with the Mushroom Stock Cube (1) and mix until well-incorporated.
Place onto parchment paper or foil, and roll tightly, making sure to remove any bubble or air. Twist the ends to secure. Place in the fridge for about 40 minutes till set or in the freezer for 20 mins.
To the Ground Beef (500 gram) add the Soy Sauce (2 tablespoon) and the Ground Black Pepper (1/2 tablespoon) and mix to incorporate.
Depending on how many or how big you would like your patties, divide your mince beef. I usually make 3-4 patties from 500g mince.
Slice the chilled butter into rounds.
Take one quarter of the mince beef and divide in half, then flatten into a small thin patty, top with a slice of mushroom butter and top with the other half of the mince. Secure edges, making sure the the butter is enclosed.
Heat Oil (to taste) in a pan and fry until the one side has formed a crust. Flip, and place a slice of Fresh Smoked Mozzarella (1) (this adds a great smokey flavor), place a lid on the pan to melt the cheese.
Finally, assemble your burger! I use toasted Brioche (to taste), but any roll of choice will do. Also, I like Dill Pickle (to taste) and Lettuce (to taste) on my burger and Ketchup (to taste) and Mayonnaise (to taste).