Prepare the veg, fruit, and dressing:

Cup of Yum
1. Wash/scrub the potatoes and put in a pot of cold water. Add about a teaspoonful of salt and bring to a boil, then simmer until cooked (check by inserting a skewer or toothpick into the center). Remove the potatoes and put on a plate, but do not discard the water. 
2. Bring the water to a boil and add the carrots for one minute, then remove. Chop the carrots into small pieces.
3. Peel the potatoes while still warm. Mash half or more of the potatoes in a large bowl, and chop the rest into bite sized pieces.
4. In a jug or medium sized bowl, whisk together the mayonnaise, mustard, vinegar, pinch of sugar and black pepper until a smooth consistency is acheived.

Mix the Korean potato salad together:

1. Add the chopped potatoes, carrots, celery, cucumber, and apples to the bowl of mashed potatoes. You can mix or omit whatever you choose. Traditional gamja salad doesn't have celery, but I sometimes add it. Sprinkle with Kosher salt and black pepper, if desired.
2. Pour the creamy dressing over the vegetables and fruit. Mix well.
3. Add the chopped hard boiled eggs and mix again, gently. Once mixed, cover and refrigerate until ready to serve. You can just serve as is in a bowl (I added a celery leaf).
4. Or you can make individual servings in bowls using an ice cream scoop, which is the traditional way to serve it with Korean bbq.