Trim core from romaine and tear or chop leaves into roughly 1- to 2-inch pieces. Rinse thoroughly in cold water, spin or pat dry until leaves are mostly moisture-free. Place romaine in a large salad bowl.

Prepare tomatoes

Core tomatoes if necessary and cut into 8 wedges (or bite-sized slices). Add to the bowl with the romaine.

Add olives and onion

Pit and halve the Kalamata olives if needed and scatter over the greens. Thinly slice the red onion into half-moons, separate the slices, and add to the salad. If using cucumber, peel (optional) and slice into half-moons and add now.

Toss lightly just before dressing: gently toss the romaine, tomatoes, olives, and onion to combine so ingredients are evenly distributed.

Vinaigrette

Emulsify dressing

In a small bowl or jar, combine red wine vinegar, Dijon mustard, minced garlic, honey (or sugar), salt, pepper, and dried oregano if using. Whisk briefly to blend. While whisking constantly, slowly drizzle in the extra-virgin olive oil until the dressing is fully emulsified and slightly thickened. Alternatively, place all ingredients in a jar, secure the lid and shake vigorously for 30–45 seconds.

Adjust seasoning

Taste the vinaigrette and adjust salt, pepper, or vinegar to balance acidity and seasoning. If too sharp, add a touch more honey; if too flat, add 1/2 tsp more vinegar.

Dress the salad

Just before serving, pour about half of the vinaigrette (approximately 2 tbs) over the salad and toss gently to coat. Add more vinaigrette to taste, tossing between additions to avoid overdressing. Serve immediately.