There is something fundamentally simple about a meal that relies on just a handful of high-quality ingredients. Early in my career, I found myself rushing through lunches, settling for processed options that left me sluggish by 3 p.m. One afternoon, while staring at a handful of Romaine hearts and a spare tin of wild-caught tuna, I decided to simplify. I wanted that classic tuna salad profile but stripped of the heavy, mayo-laden calories that often hide the real flavor of the fish.

The result was this recipe. The key isn't just the tuna—it's the interplay of textures. You have the firm, meaty flakes of the tuna, the sharp, refreshing snap of the diced celery, and the cool, hydrating crunch of the lettuce leaf. When you take that first bite, the bright acidity of the lemon juice cuts right through the richness, while the Dijon mustard adds a subtle, earthy depth that lingers just long enough to keep you interested.

1. Prepare the Tuna: Start by draining your tuna thoroughly. If there is excess liquid, the wrap will become soggy within minutes. Transfer the tuna to a mixing bowl and use a fork to break up the large chunks, but leave some texture; we want a rustic feel, not a fine paste.
2. Mix the Dressing: In the same bowl, fold in the Greek yogurt, finely diced celery, red onion, and fresh parsley. Add the lemon juice and Dijon mustard. Stir until just combined—you want to see the vibrant colors of the herbs contrasting with the tuna.
3. Seasoning: Add a pinch of sea salt and a generous grind of black pepper. Taste it. Does it need more acid? A tiny extra squeeze of lemon often wakes up the whole dish.
4. Assemble: Wash your Romaine leaves and pat them bone-dry. Lay them out, spoon about two tablespoons of the mixture into the center of each leaf, and finish with a slice of radish if you like that extra peppery kick. Serve immediately.

This dish is fantastic for meal prep, provided you keep the components separate. The tuna mixture will keep in an airtight glass container in the refrigerator for up to three days. However, do not pre-assemble the wraps; the moisture from the tuna will break down the integrity of the lettuce leaves, leading to a limp, unappetizing result. Keep your lettuce hearts whole in a container with a dry paper towel to absorb excess moisture, and assemble your wrap right before you sit down to eat.