Combine the rolled porridge oats and vegetable stock in a saucepan.Heat over medium heat, stirring occasionally, until the mixture comes to a gentle boil.
Reduce the heat to low and simmer for about 3 minutes, allowing the oats to absorb all the liquid.
Stir in the miso and butter until fully dissolved. Adjust the flavor with a pinch of salt and pepper.
Transfer the porridge to a serving bowl and top with poached egg, green onions, avocado, and sesame seeds.