An egg steamed into an egg custard with sesame oil, soy sauce and salt will increase the calories, right?

Slightly more calories than a poached egg.

If you make a custard with one egg in water and nothing else, it's the same calorie count as a poached egg,

but most of them have to be filled with something else, so the calorie count will be a little bit higher,

but it's negligible unless you put a lot of oil in it.