Open-faced avocado and tuna sandwich

SALAD INGREDIENTS

1 6oz can solid white albacore tuna (in water, drained)
1 to 2 tbsp mayonnaise
1/2 cucumber, diced
2 tbsp red onion (or 1 small shallot), diced
1 to 2 tbsp dill pickle relish (not sweet)
ground black pepper
1/2 avocado, diced
1/2 cup cherry tomatoes, halved
1/2 of the juice from a small lime
sea salt to taste

SANDWICH INGREDIENTS

1 to 2 handfuls of lettuce
rustic baguette (halved and toasted) (or whatever type of bread you want)