Separate the romaine leaves and rinse them thoroughly in a large bowl of cold water to remove any grit or sand trapped between the layers. Lift the leaves out of the water rather than draining them so debris stays at the bottom of the bowl. Dry the lettuce completely using a salad spinner or a clean kitchen towel. Properly dried leaves ensure the dressing coats the lettuce evenly instead of sliding off diluted by water.

Stack several romaine leaves together and slice them crosswise into bite-sized pieces about 3–4 cm wide. Romaine should remain crisp and structured, so avoid cutting it too finely. Transfer the chopped lettuce to a large mixing bowl that provides enough space for tossing the salad later.

Rinse the parsley thoroughly and dry it completely. Remove any thick stems and roughly chop the leaves into small pieces. The parsley should remain slightly rustic rather than finely minced so its bright herbal flavor is clearly noticeable throughout the salad. Add the chopped parsley to the bowl with the romaine lettuce.

Wash the cucumber and trim the ends. Slice it into thin rounds approximately 3 mm thick using a sharp knife or mandoline. Thin slices distribute evenly throughout the salad and add refreshing crunch without dominating the texture. If the cucumber has large seeds, slice it lengthwise and remove the seeds before cutting.

Rinse the cherry tomatoes and dry them with a clean towel. Slice each tomato in half lengthwise to expose the juicy interior. If the tomatoes are particularly large, cut them into quarters so they distribute evenly through the salad.

Peel the red onion and slice it very thinly into half-moons. Thin slicing ensures the onion adds subtle sharpness without overpowering the other ingredients. If the onion flavor is very strong, place the slices in a bowl of cold water for 5 minutes, then drain and pat dry before adding to the salad. This step softens the sharp sulfur compounds and creates a milder flavor.

In a small bowl combine fresh lemon juice, extra virgin olive oil, minced garlic, dried oregano, salt, and black pepper. Whisk vigorously for about 20 seconds until the oil and lemon juice begin to emulsify into a smooth dressing. Allow the dressing to rest for 3–5 minutes so the garlic and oregano infuse into the vinaigrette.

Add the cucumber slices, cherry tomatoes, and red onion to the bowl containing the romaine and parsley. Toss the vegetables lightly to distribute them evenly before dressing.

Drizzle the lemon dressing evenly over the salad. Using salad tongs or clean hands, gently toss the salad until all leaves and vegetables are lightly coated with the vinaigrette. Avoid overmixing, which can bruise the lettuce.

Transfer the salad to a serving bowl or individual plates and serve immediately while the lettuce is crisp and fresh. Because the dressing is light and acidic, the salad pairs especially well with grilled meats, roasted vegetables, seafood, or pasta dishes.