Whisk mayonnaise, lemon juice, tomato paste, shallot, Dijon mustard and pepper in medium bowl.
Cover and refrigerate until ready to use. (Can be prepared 3 days ahead.)
Cook asparagus in large pot of boiling salted water until crisp-tender, about 4 minutes. Transfer to bowl of ice water and cool. Drain and pat dry. mix crabmeat into mayonnaise.
Season to taste with salt. Arrange 1 lettuce leaf on each plate. Top with asparagus. Spoon crabmeat mayonnaise over and serve.