Preheat a frying pan over medium-high heat.

Combine lime juice with maple syrup or honey in a bowl or container. Set aside.

Brush the tuna steak with oil and season with salt and pepper. Sear for about 45 seconds on each side, then transfer directly to the lime-maple mixture.

Allow to marinate for one hour or up to overnight.

Combine lime juice, maple syrup, mayonnaise, dried chives, and garlic powder.

Season to taste with salt and pepper, and thin with one to two tablespoons water until you have a dressing consistency.

Combine onion, tomato, cucumber, cabbage, and carrots.

Toss with dressing and serve inside a bib lettuce leaf.

Top generously with chopped parsley and cilantro.

Slice the tuna thinly and serve alongside the lettuce taco for optional inclusion.