(I made it in a hurry, but I don't have a picture in the beginning. I will update it when I make it next time.)
The most important thing in stir-fried potatoes is to take out starch from potatoes. That way, it's not sticky and has a clean taste.
First, prepare the potatoes, soak them in cold water, and start preparing the carrots.
Here, 'handling' is the ingredients that have been cut into small pieces.
When you are done preparing the carrots, cover the frying pan with oil and heat it over medium heat.

Add potatoes and carrots after 10-20 seconds of heating the pan
I cut it into this thick pieces
It's good to mix it with rice and eat it with chopsticks.

Now prepare the onions. While preparing the onions, use a spatula to keep the potatoes and carrots from burning.
When the onions are finished, put them in a pan and cook the ingredients over low heat until the ingredients are cooked.

(But if the moisture goes away quickly, it has a rather crispy texture or burns well.). So I cover the ingredients with something that I can cover. A pan with a lid would be nice, but without a lid. Put the ingredients together and cover with the largest bowl.)
It's slightly cooked on the surface, but it doesn't bend when you lift the potato.
Cover it with a bowl, lid, etc., and cook it for 5-7 minutes more on low heat (the cooking time varies depending on the weather, so try one more, and cook it more while looking at the condition).