Combine chicken stock and eggs in a mixing bowl.Whisk to combine well and season with a pinch of salt. Pour into two small shallow bowls.
Using a spoon, skim off any bubbles. Or if you have one, use a blow torch to pop the bubbles on the surface.
Place a steaming rack or steaming basket in a large pot with a lid.Make sure your chosen bowls will fit in the pot. Pour a couple cm of water into the pot and bring to a simmer.
Gently place bowls with egg mixture into the steamer and cover immediately.Leave the lid ever so slightly cracked for steam to escape.
Steam until egg mixture is set and jiggly when shaken, 12–15 minutes.
For the mushrooms
While the eggs are steaming, prepare the mushrooms. Slice the portabellinis and heat the butter and sesame oil in a frying pan.
Add the mushrooms and cook until golden brown. Towards the end, pour in the soy sauce and toss to coat well.
Carefully remove the bowl from the steamer using a dish cloth.
Top steamed eggs with soy butter mushrooms and all the cooking liquid. Finish with freshly ground black pepper and a generous sprinkle of chives. Serve and enjoy!
*** Top tip:You can also prepare the steamed eggs in the microwave for ease and speed. Cover the egg mixture bowl with a microwave-safe plate.Reduce your microwave to 300-400 watts.Microwave for ± 5 minutes until the eggs have just set and are no longer liquid in the middle.(Every machine differs quite significantly, so check for doneness at 4 minutes, then in 30-second intervals after that if needed.)