Take the tuna out of the fridge to acclimatise to room temperature.
The tuna should ideally be taken out of the freezer the night before to defrost in the fridge.
Cut the avocado in half, peel and de-seed it, and chop into cubes.
Roughly chop the onion, quarter the tomato, and finely chop the parsley.
Add the chopped vegetables to the avocado. Add the lime juice and a little olive oil. Season with salt and pepper. Carefully toss together and set aside in the fridge to chill.
Drizzle the baguette with oil and heat the grill.
Pat the tuna dry with kitchen towel and drizzle with olive oil. Place on the grill for around a minute and a half on either side. Finally, grill the baguette.
Give the fish a moment to rest and then cut into slices.
Plate up the avocado salad, the baguette, and the tuna slices. These should be seasoned with pepper and Maldon salt to finish.