Spring Asparagus Tart

Name: Spring Asparagus Tart
Ingredients: 1 tablespoon all-purpose flour, plus more for dusting; 1 sheet frozen puff pastry, thawed (a 9 1/2- by 9-inch sheet from a 17.3-ounce package); 1 cup mascarpone; 1 1/2 teaspoons kosher salt; 1 large egg, beaten; 1 lemon, zest finely grated (about 1 tablespoon); 1 tablespoon chopped fresh chives; 1 tablespoon chopped fresh tarragon; 1 pound pencil asparagus, woody bottoms trimmed off; 1 tablespoon olive oil; Freshly ground black pepper; Lightly dressed greens, for serving