The toasted pumpkin seeds and sardines make this a crunchy, healthy midday meal.
Whisk lemon zest and juice with olive oil. Season with salt and pepper.
Arrange watercress, red onion, and tarragon on a platter.
Top with clementine slices, sardines, and pumpkin seeds. Season with salt and pepper. Drizzle with vinaigrette, and adjust seasoning, as necessary.