We limited the marinating time to 2 hours because lemon juice tends to discolor and toughen asparagus.
Whisk together lemon juice and next 5 ingredients in a large bowl; add artichoke quarters and diced pimiento, and gently toss. Cover and chill 8 hours or overnight.
Snap off tough ends of asparagus; cook in boiling salted water to cover 3 minutes or until crisp-tender.
Drain asparagus, and plunge into ice water to stop cooking process. Place cooked asparagus in a large heavy-duty zip-top plastic bag, and store overnight in refrigerator, if desired.
Add asparagus to artichoke mixture, and gently toss. Cover and chill 2 hours. Garnish, if desired.