In a large, deep skillet of boiling salted water, cook the asparagus over high heat until crisp-tender, about 5 minutes. Drain the asparagus and refresh in a bowl of ice water. Drain and pat dry.
In a large bowl, mix the oil with the vinegar. Add the crabmeat, bell peppers, onion and tarragon and season with salt and pepper. Transfer the asparagus to a large, deep platter, spoon the crab vinaigrette over the top and serve.
The asparagus and vinaigrette can be refrigerated separately for 6 hours.