Wash the lettuce leaves thoroughly under cold water. Spin or pat dry until mostly moisture-free. Tear or chop into bite-sized pieces and place into a medium mixing bowl (about 3 cups loosely packed).

Tomato and cucumber

Core the tomato and cut into 8–10 wedges or 1/2-inch dice depending on preference. Add the tomato pieces to the bowl. If using cucumber, thinly slice or half-moon slice and add to the bowl.

Onion and herbs

Slice the red onion very thin (use a mandoline or sharp knife) and separate the rings. Scatter 2 tablespoons of the sliced onion over the salad. If using parsley, finely chop and sprinkle over the greens.

Sunflower seeds

If the sunflower seeds are not toasted, warm a small dry skillet over medium heat, add the 2 tablespoons of hulled sunflower seeds and toast, stirring, for 1–2 minutes until fragrant and lightly golden. Remove from heat and allow to cool for 30 seconds, then sprinkle over the salad just before dressing to retain crispness.

Dressing

Combine dressing ingredients: In a small bowl or jar, add 1 1/2 tablespoons extra-virgin olive oil, 1 tablespoon fresh lemon juice, 1/2 teaspoon Dijon mustard, 1/2 teaspoon honey (or maple syrup), 1/4 teaspoon salt, and 1/4 teaspoon black pepper.

Emulsify: Whisk vigorously with a small whisk or fork for 20–30 seconds (or put the jar lid on and shake vigorously for 15–20 seconds) until the dressing is emulsified and slightly thickened. Taste and adjust seasoning: add a pinch more salt, pepper, or a drop more honey or lemon if desired.

Dress the salad: Drizzle dressing evenly over the salad (use about half to three-quarters of the dressing and reserve the rest for another use). Gently toss the salad with tongs or salad servers until the leaves, tomato, and cucumber are lightly and evenly coated.

Serve: Transfer the dressed salad to an individual serving plate or bowl. Sprinkle the toasted sunflower seeds over the top for crunch. Serve immediately.