Preparations:

Preheat oven to 100C. Heat oil in a frying pan and cook bacon to your liking then keep in oven to warm.

For sauce, whisk yolks and lemon juice together in a small heatproof bowl. Place bowl over a saucepan of barely simmering water (make sure bowl doesnt touch water). Add 1 piece of butter. Whisk until melted. Continue adding butter, 1 piece at a time, whisking after each addition, until sauce starts to thicken. Once this happens you can add 3-4 pieces at a time, continuing until all butter has been added. If bowl gets too hot remove from heat and continue adding butter, then return to pan. If sauce is too thick, add a little hot water. Season to taste with salt and pepper.

Grill portobello mushrooms for 5 mins and place on plates and top with bacon and poached eggs. Spoon over hollandaise sauce.