Clean the potatoes and chop them into 3/4" size pieces. In a large pot of salted boiling water, add the chopped potatoes and boil for about 8-10 minutes until they are fork tender.
Remove the pot from the heat and drain the potatoes. Promptly return them to the pot they were cooking in (NOT over heat) to let them steam for a bit.
Chop the bacon into 1/4" pieces and add it to a frying pan over medium high heat. Cook for 3-4 minutes until bacon starts to brown and add the diced onions. Cook for an additional 8-10 minutes until the bacon is crispy and the onions are browned.
Add the cooled bacon and onions to a large bowl with the potatoes, celery, green onions, bell pepper and hard boiled eggs.
In a separate bowl, combine the mayonnaise, Dijon, vinegar, salt, pepper and mashed roasted garlic. Mix well and spoon on the top of the potato mixture. Gently fold the dressing into the vegetables until well combined.
Chill in the refrigerator for 2 hours before serving.