Directions

1. Prepare an ice-water bath; set aside. Coarsely chop enough tarragon leaves to make 6 tablespoons, and set chopped leaves aside. Reserve remaining sprigs for garnish. Bring a small saucepan of water to a boil; add 1 teaspoon salt. Add scallions, and cook until bright green and just tender, about 1 1/2 minutes. Add tarragon leaves, and cook until bright green, about 20 seconds; immediately transfer scallions and tarragon to the ice-water bath. Let cool completely.
2. Drain scallions and tarragon, then squeeze dry in a clean kitchen towel. Coarsely chop, then transfer to a food processor; pulse until finely chopped. Add mustard. With machine running, add oil in a slow, steady stream; process until smooth and thickened, about 1 minute. Transfer to a small bowl; stir in creme fraiche. Cover, and refrigerate until ready to serve (up to 2 days).
3. Prepare an ice-water bath; set aside. Place a dozen eggs in a saucepan large enough to hold them in a single layer; cover with cold water by 2 inches. Bring to a boil, then reduce heat, and simmer 1 1/2 minutes. Using a slotted spoon, transfer eggs to the ice-water bath, and let cool. Meanwhile, repeat with remaining eggs. Peel eggs, dipping them in cold wa��ter if needed to remove shell pieces. (Peeled eggs can be refrigerated in an airtight container overnight.)
4. Pick 4 dozen small leaf clusters from remaining tarragon sprigs; set aside. Halve eggs lengthwise. Arrange blini on a platter. Spoon 1/2 teaspoon sauce in center of blini. Top each with half an egg, 1/4 teaspoon roe, and a tarragon cluster.