How to Make It
Using a fork, finely crush eggs in a medium bowl. Stir in mayonnaise, mustard, dill, chives, scallions, brine, hot sauce, salt, and pepper.
Bring a medium saucepan of salted water to a boil over high. Fill a large bowl with ice water. Cut tip ends of asparagus spears into 4-inch lengths (the same length as bread slices); discard remaining asparagus spears or reserve for another use. Cook asparagus tips in boiling water until tender-crisp, 30 seconds to 1 minute; drain. Plunge into ice water to stop the cooking process; drain and pat dry.
Spread butter evenly on toasted bread slices; cut bread slices in half lengthwise. Spread egg mixture evenly over butter; top with 2 or 3 asparagus tips. Serve immediately, or cover with damp paper towels, and chill up to 1 hour.