Tuscan white bean salad with tuna

This recipe is from cookbook called Super Salads. As son as I saw this recipe I remembered my mom used to make Turkish recipe called "piyaz". It is meze ( side dish) and very famous in Turkey. We mostly eat with kofte ( Turkish meatball). That recipe didn't have tuna. I used tuna with water but recipe used tuna with oil. 
Ingredients

2 cans (14oz) each white beans,
drained and rinsed
2 can ( 15 oz) tuna with water
1 medium red onion, sliced
3 tbsp olive oil
1 lemon juice
1 tbsp chopped fresh parsley
Preparation Method
Toss beans,tuna, onion, oil, lemon juice and parsley together in a large serving bowl.
Sprinkle with chopped parsley just before serving.