If you like rare tuna, this is a real treat. It is not only delicious, but also makes a stunning presentation. The preparation time is only 5-10 minutes, but your guest will think you slaved for hours.
This recipe does not require much cooking, so its success completely relies on the quality of the ingredients. Make sure to use very fresh Grade A tuna. Use the best hummus you can find (Middle Eastern and Organic stores often have better hummus than regular supermarkets). The olives are pretty flexible as long as they are brine-cured - the kind you would serve with bread and cheese for appetizer. Niçoise, green, kalamata, or some combination of these olives work well with tuna. Since olives start becoming acidic after pitting, buy your olives with pits, and pit them shortly before serving.