This is the side dish I make more than any other side dish around our house. It's cheap, it takes under 10 minutes from start to finish, it's healthy and it's unexpected. I just love it.
To start, remove any sad looking leaves from the outside of the romaine and slice it in half keeping the root intact because it holds the leaves together. Drizzle both sides with olive oil, salt and pepper, and throw on the grill (or under the broiler on an aluminum sheet pan in winter). Broil on high for 3-4 minutes per side until it's charred and you're done.
As you can see, I threw some green onions on the pan as well because charred green onions are delicious.
To serve, I like to chop up the romaine and green onions and top with dressing and grated Parmesan cheese. Don't forget to chop off the root end before serving. But when I'm feeling lazy, I just serve the romaine lettuce whole with a fork and knife and call it rustic.