This simple salad really shines when you use good fresh lettuce. You can keep it simple (as we did) with just tender butter lettuce leaves, or explore arugula, leaf lettuce, baby kale, baby mustard greens--whatever looks good at the market. In season, definitely check out what's available at farmers markets, or consider planting mixed lettuce seeds in your backyard in spring and fall.
This recipe is just a blueprint: Have fun improvising! You can substitute a different nut, firm cheese or herb. Or skip the nuts, and toast some panko in olive oil to make a crisp breadcrumb rubble (like crumbled croutons) that will get caught in the lettuce. You can even add another vegetable—fine slivers of shallot, snap pea, fennel or radish. Just remember, you want to enhance the lettuce, not compete with it.