Wash and scrub the potatoes, then cut them into evenly sized chunks.
Place them in a large pot, cover with cold water, and add 1 tablespoon of salt. Starting with cold water ensures even cooking.
Bring to a boil and cook until tender (about 15-20 minutes). Test with a fork - they should be soft but not falling apart.
Drain and let them cool slightly. Optionally, you can spread them on a baking sheet while still hot to prevent them from becoming too mushy.
In a large bowl, whisk together the mayonnaise, Dijon mustard, garlic powder, salt, and pepper. Optionally you can add apple cider vinegar or pickle juice for extra tang (to taste).
Once the potatoes have cooled slightly but are still warm, add them to the dressing (mixing while warm allows them to absorb more flavor).
Gently fold in the chopped hard-boiled eggs and red onion. Be careful not to overmix to maintain the potato texture.
To chill the salad, cover it and refrigerate for at least 1 hour (or preferably overnight) to let the flavors meld. Make sure the bowl is tightly covered to prevent the salad from absorbing other fridge odors.
Before serving, taste and adjust seasoning if needed. A little extra salt, pepper, or vinegar can brighten the flavors.
Garnish with fresh parsley, dill, or a sprinkle of paprika for a beautiful finishing touch.