Put beets in a saucepan with water to cover and season with salt. Bring to a boil over high heat and cook until fork tender, about 20 minutes. When the beets are cool, peel and cut into bite-sized wedges.
Whisk together the mustard, vinegar and a pinch of salt and pepper. Gradually whisk in oil, until the dressing is emulsified.
Pour about half the dressing over the beets. Sprinkle in chopped herbs. Season generously with pepper. Toss well, then taste and adjust seasoning, adding more dressing or salt as needed. Let sit for at least 20 minutes before serving.