Season mushrooms with salt and pepper, add crushed garlic and freshly chopped herbs and ghee, preferably melted. Keep some of the ghee for frying the eggs. Keep the mushrooms at room temperature and marinate for up to an hour. 

Place the mushrooms top side up on a hot pan. Cook over a medium-high heat for about 5 minutes each side.

Take off the heat. Flip back on the top side and top each of the mushrooms with cheese slices. Just before serving, place under a broiler for a few minutes until the cheese has melted.

Meanwhile, fry the eggs on the remaining ghee. Cook the eggs until the egg white is opaque and the yolks still runny. Then, take off the heat.

Cut the buns in half and place each halve, cut side down on a hot griddle pan and cook for 2-3 minutes until crispy.

Start assembling the burgers by adding a tablespoon of mayo on each of the bun halves. Top with portobello mushrooms, fried eggs a slices of tomato and lettuce.