Place eggs in a pot. Cover them with cool water by 1 inch. Cover with a lid and bring the water to a boil over medium high heat; once the water has reached a boil, set a timer for 5 minutes. (For runny yolks set the timer for 2 minutes)
At the same time, melt the butter in a nonstick pan over medium heat. Add in the mushrooms and onions and cook for 7 - 10 minutes until they are soft. Push the mushrooms and onions to one side of the pan and warm the pastrami slices in the other half. Toast the bread.
Using a slotted spoon, transfer the eggs to a bowl and let them sit for 1 - 2 minutes before peeling the eggs.
Layer the toast with pastrami and spread the mushroom and onions on top, serve with peeled and halved soft boiled eggs on the side. Garnish with chives and orange sections on the side.