Wash the potatoes and cube. If you want to peel the potatoes you can but it is not a must.
Fill a pot with cold water and add the potatoes to the water.
Over high heat bring the potatoes to a boil and boil potatoes in a pot until they are soft enough that you can stab them with a knife easily about 15 minutes), then drain. Rinse potatoes with cold water and add to a large bowl.
While potatoes are cooking wash and chop the veggies.
Add chopped veggies, salt, pepper, mayo and mustard to the bowl and mix everything well.
Chill in the fridge for at least 30 minutes to have the flavors mix together.