Step 1 Combine the mustard, 2 tablespoons vinegar, shallot and the chives in small bowl and whisk to blend. Whisk in the oil. Season with salt and pepper to taste. Set aside.
Step 2 Blanch the pancetta pieces in a small pan of simmering water for 10 minutes. Drain on paper towels.
Step 3Heat a small skillet over medium-high heat. Add the pancetta and cook, stirring constantly, until the fat is rendered and the meat is cooked but not crisp, 4 to 5 minutes. Remove with a slotted spoon to a plate lined with paper towels. Immediately add the bread cubes and cook, stirring constantly, until crisp, about 6 to 8 minutes. Remove and set aside.
Step 4Bring a deep skillet of water to a rolling boil. Add the remaining 1 tablespoon vinegar and one-half teaspoon salt and stir well. Reduce the heat and bring to a simmer. Break each egg into the water and poach 90 seconds. Using a slotted spoon, immediately transfer the eggs to a plate and keep warm.
Step 5Place the frisee in a large bowl and toss with the mustard dressing, pancetta and croutons. Divide among 4 serving plates. Top each salad with an egg seasoned with salt and pepper. Serve immediately.