For the salsa, finely chop the shallot, avocado, cucumber and coriander. Place in a bowl.
Add to the bowl, capers and Mutti Polpa (straight from the tin) plus the lime juice. Drizzle with olive oil, season to taste and mix. Set aside in the fridge.
Meanwhile, preheat the grill pan to medium/high.
Brush the tuna with olive oil and place on the grill pan. Cook for 4 minutes each side, so it remains pink in the centre.
Serve the tuna with the pico de gallo topping and grilled sourdough toasts if desired.