Pick individual leaves or wait and harvest full heads.
For ongoing harvest, you can begin harvesting once the leaves reach about 4 inches tall. Harvest the outer leaves of the head and let the inner leaves continue to grow and mature. Just snip either single outer leaves or grab a bunch of them and cut them with scissors one inch above the base of the plant. Be careful; if you cut into or below the base, the plant may die, so leave the small leaves in the middle to regrow easily.
Do not cut more than a third of the plant in you want it to keep growing.
Romaine is a popular lettuce for salads, taco shells, sandwiches, and wraps.
THE DRESSING: Chop together anchovy fillets, garlic, and pinch of salt. Use the side of a knife blade to mash into a paste, then scrape into a medium bowl. Whisk in egg yolks, 2 Tbsp. lemon juice, and mustard. Adding drop by drop to start, gradually whisk in olive oil, then vegetable oil; whisk until dressing is thick and glossy. Whisk in Parmesan. Season with salt, pepper, and more lemon juice, if desired.
THE CROUTONS: Make your own. Tearing, not cutting the bread ensures nooks and crannies that catch the dressing and add texture. Preheat oven to 375°. Toss bread with olive oil on a baking sheet; season with salt and pepper. Bake, tossing occasionally, until golden, 10–15 minutes.
THE LETTUCE: Use whole leaves; they provide the ideal mix of crispness, surface area, and structure.
THE CHEESE: Caesars crowned with a mound of grated Parmesan may look impressive, but all that clumpy cheese mutes the dressing. Instead, use a vegetable peeler to thinly shave a modest amount on top for little salty bursts.
THE ASSEMBLY: Skip the tongs. Use your hands to gently toss the lettuce, croutons, and dressing, then top off with the shaved Parm.