1. Combine cooked steak, capers, cornichons, red onion, Dijon mustard and 3/4 of the
mayonnaise in medium bowl; toss to blend. Season with sea salt and pepper to taste.
2. Arrange bread on clean work surface. Spread slices with remaining mayonnaise.
Divide steak salad among bread slices.
3. Top on each with 2 tomato slices and arugula. Press second bread slice, mayo side
down, onto each sandwich.