Preheat oven to 80°C.
Fill a baking dish with EVOO, just big enough for the tuna to fit in, with small gaps between. The reason for this is so you don't waste oil. Test with a piece of tuna. Then take the tuna out.
Place the EVOO in the oven until it reaches 70-80°C. Check every 5 minutes.
When it's reached temp, put the tuna in the oil and return the dish to the oven. Turn oven down to 70°C. Cook for 15 minutes exactly. Remove tuna from the oil. Press black sesame seeds onto one side, optional. You can also sear the tuna with the seeds to make it look amazing. Don't overcook it though, or you have kind of destroyed the whole point of confit.
Meanwhile, place eggs into the simmering basket and insert into the Thermomix bowl. Fill with water. Cook 5 min/100/speed 2.
Place green beans into the Varoma dish. Set Varoma into position and steam 11 min/Varoma/speed 2.
Place the beans straight into an ice bath so they keep their bright green colour. Peel cooled eggs and cut in half.
In a bowl, combine the cannellini beans, lemon juice, EVOO, salt and pepper, set aside.
Assemble salad on a platter; lettuce, tomatoes, capsicum, onion, cucumber, olives. and cannellini beans. Slice tuna and place on top, with the mayonnaise drizzled all over.