Wash the romaine or mixed greens thoroughly under cold water. Spin or pat dry with paper towels until mostly dry. Tear larger leaves into bite-sized pieces and place them in a large salad bowl.

Prepare the tomatoes

Core the tomatoes, cut into quarters or 1/2-inch wedges depending on size, and add them to the bowl with the greens.

Slice the cucumber

Halve the cucumber lengthwise, then slice crosswise into 1/4-inch slices. Add the slices to the bowl.

Slice the onion and pepper

Peel and halve the red onion, then slice very thinly (use a mandoline or a sharp knife). Remove the stem and seeds from the red bell pepper, then slice thinly. Add both to the bowl. If you prefer milder onion flavor, soak the sliced onion in cold water for 5 minutes, then drain and pat dry before adding.

Simple Vinaigrette

Combine the dressing ingredients: In a small bowl or jar, whisk together the red wine vinegar, Dijon mustard, minced garlic, and honey (if using). Slowly whisk in the extra-virgin olive oil until the dressing is emulsified. Season with salt and freshly ground black pepper and taste; adjust acidity or sweetness to preference by adding more vinegar or honey in 1/2 teaspoon increments.

If using a jar: add all ingredients, close lid tightly, and shake vigorously until well combined.

Assembly & Serving

Dress the salad: Just before serving, pour about half of the vinaigrette over the salad bowl (you can reserve the rest for guests to add more). Start with a light coating and gently toss the salad with salad tongs or two large spoons until ingredients are evenly coated. Taste and add more dressing as desired.

Add optional finishers: If using, sprinkle crumbled feta and/or toasted seeds or nuts over the top and give one gentle toss to combine.

Serve immediately: Transfer to a serving bowl if desired, or let guests serve themselves. Leftover dressing can be refrigerated in a sealed container for up to 5 days; keep salad components separate until ready to serve if making ahead.