Lay pork shabu in a single layer on a chopping board. Season lightly with salt and black pepper. Place one to two asparagus on each pork and roll it up as tightly as you can. As pork shabu is thin, it will naturally stick to itself so there's no need to skewer it sealed with toothpicks.
Heat a large non-stick pan over medium-high heat. If your pork shabu is not very fatty, you can add a little bit of oil. I don't for mine as it will render fat on its own. Place the rolls in a single layer and cook until browned, about 1 minute. Flip and cook the other side until browned, another 1 minute. Remove from the pan and set aside. (The rolls don't have to be fully cooked as they will cook again in the sauce later on). Repeat until all rolls are browned, draining off excess oil as you cook.
Whisk the sauce ingredients together in a small bowl. Reduce the heat to low and pour in the sauce. Bring the sauce to a simmer (it's almost immediate as the pan would be very hot). Return the rolls and any leftover pork shabu or asparagus into the sauce and simmer, turning the rolls frequently, until the rolls are cooked and the sauce has thickened, about 2 to 3 minutes.
Transfer the rolls onto a serving plate and pour over the sauce. Sprinkle sesame seeds on top and serve.
NOTES
Baby asparagus is recommended as it cooks through faster than regular asparagus.
Either pork collar shabu or pork belly shabu can be used. I personally prefer pork collar shabu as it's slightly less fatty. Do use a good-quality pork shabu (I like iberico or kurobuta) with fats for tenderness and flavour.
I usually do a rough count of how many pork shabu and baby asparagus I have to determine whether to wrap one or two asparagus per pork shabu.