Season the tuna with salt to taste. Sprinkle the cracked black pepper onto a plate and press the tuna onto the cracked pepper.
Brush a griddle pan with half a teaspoon of the olive oil and place over a medium heat.
Griddle the tuna for one minute on each side and remove the tuna from the heat. Keep warm.
Brush the ciabatta with a teaspoon of oil and griddle for two minutes until slightly browned on both sides. Set aside.
Heat a separate frying pan, add the remaining olive oil and the peppers and courgette to the pan. Season, to taste, with salt and freshly ground black pepper.
Fry the peppers and courgette for three minutes, before adding the garlic and thyme to the pan. Fry for a further three minutes. Add the cherry tomatoes and balsamic vinegar, stir to combine and then tip the contents of the pan into a mixing bowl.
Add the anchovy fillets, capers and black olives to the bowl and stir to combine.
To serve, slice the tuna into thin pieces. Place a slice of ciabatta on each of four plates, spoon over the pepper mix and arrange a slice or two of tuna on top.