Preheat your grill on high heat. Scrape the grates clean and turn all burners to low.
Whisk together the vinaigrette ingredients (fresh pineapple juice through fresh ground black pepper. Pour about half of the vinaigrette over the steaks to marinate. Pour a couple of tablespoons of the vinaigrette over the asparagus spears and onion slice. Allow the steak to marinate for 20 - 30 minutes.
Grill the steaks until the internal temperature reads 155 degrees F. Remove the steaks to a cutting board and rest for at least 5 minutes.
Grill the asparagus spears until crisp tender (just about 5 minutes) and grill the onion slice on both sides until browned and starting to soften.
Cut the grilled onion into bite-sized pieces and slice the steak.
Place a pile of butter lettuce on each plate and top evenly with the grilled steak, pineapple, grilled asparagus and onion. Top evenly with the reserved pineapple vinaigrette dressing.