Cut potatoes in 1/2 and arrange in a single layer, cut side down
Add water, butter, garlic, thyme, salt and pepper and 1 tsp of Dijon
Simmer over medium high heat, cover 15 minutes
Remove garlic to cutting board
Swirl pan frequently 15-20 minutes
Once garlic has cooled move to a bowl & make into a paste, combine with remaining Dijon and salt and pepper to taste
Continue to cook potatoes 4-6 minutes till brown
Off heat toss with garlic mixture and tarragon