Mix together three quarters of the olive oil, three quarters of the chopped shallots, the chopped basil and the sun-dried tomatoes in a mixing bowl. Marinate the tuna fillet for 15-20 minutes.
Meanwhile, heat the remaining olive oil in a wide heavy-based saucepan over a medium heat. Add the remaining shallot and fry for 2-3 minutes. Add the tomatoes and continue to cook for a further 5 minutes. Add the bay leaf and parsley and remove from the heat.
Heat the grill to hot. Thread a garlic clove onto the bay twigs or skewer, then two cubes of the tuna fillet. Grill for 6-8 minutes, until seared on the outside and pink on the inside.
Reheat the tomato and shallot salad and remove the bay leaf. Season to taste. Transfer to serving bowls and serve with the tuna kebabs on plates.