In a small bowl, whisk together half the smashed garlic, lemon juice, lemon zest and olive oil in a bowl. Add sea salt and pepper to taste. Pour over the fresh tuna steaks to marinate for 15 minutes. Set aside.
In another small bowl, whisk together the rest of the garlic, lemon juice, lemon zest, olive oil and dijon mustard adding sea salt and pepper to taste. Set aside, this is your dressing.
Grill the tuna steaks. About 4 minutes per side. Until just marked on the outside and a tiny bit pink in the center. Remove from the grill and let cool slighty. Break into uneven medium size pieces.
In the pot that you cooked your pasta in, toss together the cooked pasta and the dressing. Add the drained capers, olives, cherry tomatoes, and cooked fingerling potatoes. Toss to coat with the dressing. Adjust the seasonings.
Arrange pasta onto four soup plates. Add the grilled tuna pieces, the cooked haricot verts attractively atop.
Cut the egg into quarters and add to the arrangement. Top with two anchovie filets, and an additional squeeze of meyer lemon.