Drain the tuna thoroughly: Open the tins and tip the tuna into a fine-mesh sieve. Press down gently with the back of a spoon to remove as much liquid as possible. You'll see the tuna flake apart easily, and the surface should look dry rather than shiny. Getting rid of that extra moisture is the secret to a creamy, not watery, salad.

Prepare the vegetables: On a cutting board, dice the red onion, celery, and red bell pepper into small, even pieces – about the size of a pea. You want them to blend into the salad rather than dominate each bite. The onion should smell sharp and fresh, and the celery will release a faint, grassy aroma as you chop.

Mix the tuna base: In a large mixing bowl, combine the drained tuna, diced vegetables, and chopped parsley. Use a fork to break up any large tuna chunks until the mixture looks uniform, with flecks of green and red scattered throughout. The texture should be chunky but cohesive.

Add the binding ingredients: Spoon in the mayonnaise, Dijon mustard, and lemon juice. Sprinkle over the salt and pepper. Stir everything together with a spatula until the dressing coats every flake of tuna. The colour will turn a pale, creamy yellow, and you'll hear a soft squelching sound as the ingredients combine. Taste and adjust seasoning – it should be tangy and savoury.

Prepare the avocado halves: Using a sharp knife, cut each avocado in half lengthways around the stone. Twist gently to separate the halves. Remove the stone with a spoon. If you want a larger cavity for the filling, scoop out a tablespoon of avocado flesh from each half and dice it, then fold it into the tuna salad. The avocado halves should look like little green boats, with a smooth, buttery surface.

Fill the avocado halves: Spoon the tuna salad generously into each avocado cavity, mounding it slightly on top. Press down lightly with the back of the spoon so the filling stays in place. You should see the salad peeking above the edge of the avocado, creating a beautiful contrast of green and creamy tuna. If using, sprinkle a pinch of smoked paprika over the top for a pop of colour and subtle smokiness.

Serve immediately or store for later: If eating straight away, the avocados will have a cool, creamy texture and the tuna will be refreshingly tangy. For meal prep, see the tips below for storing the components separately.