Melt butter in a pan, add olive oil, the sliced onions and a pinch of salt. Cook them down until they caramelise and then add them to a blender with the miso paste, chicken stock and lemon juice.
Blitz until smooth and then add back to the pan.
Meanwhile, boil the ramen noodles according to package, drain and then add to the oniony sauce.
Mix well and serve on a plate with the egg yolk, sesame seeds and spring onion!
