Peel the potatoes and halve them lengthwise. Cover with cold water and add a tablespoon of salt. Cook until just tender but not soft or falling apart. Check with the point of a sharp knife.
While the potatoes cook, fry the bacon until crisp. Reserve the grease. Drain the bacon on paper towels and then finely chop or crumble and set aside.
In a small saucepan mix 1/4 cup of the reserved bacon fat, the vinegar, sugar, salt, celery seed and Dijon mustard. Whisk to combine and keep warm over a very low heat. Note: taste the dressing to adjust any of the ingredients. Remember the vinegar taste will mellow out once you mix it with the warm potatoes.
Drain the potatoes and thickly slice while still hot. Don't worry if they are a little soft and starting to fall part, just scrape it all into a large serving bowl along with the celery, onion, and crumbled bacon. Toss gently with the hot bacon vinaigrette.
Top with the fresh herbs, and some fresh cracked black pepper. Serve immediately.
Notes
*Try to choose potatoes of similar size so they'll cook evenly.