Lentil Tuna Salad

I found this recipe from cookbook called 1000 low fat. We like spicy food so I added jalapeno pepper.  This recipe is our another favorite dish. We loved it.
Ingredients
2 ripe tomatoes
1 chopped jalapeno pepper ( optional) 

1 small red onion
3 tbsp olive oil
1 tbsp lemon juice
1 tsp whole-grain mustard
1 garlic clove, crushed
1/2 tsp ground cumin
1/2 tsp ground coriander
1 cup dry lentil, boiled until cooked and drain
2 7 oz can tuna, drained
2 tbsp chopped cilantro
salt and pepper
Preparation Method
Using sharp knife, deseed the tomatoes and then chop them into fine dice. Finely, chop the red onion.
To make dressing, whisk together the olive oil, lemon juice, mustard, garlic, cumin and ground coriander in a small bowl until thoroughly combined. set aside until required.
Mix together the chopped onion, diced tomatoes, and drained lentils in a large bowl.
Flake the tuna with fork and stir it into the onion, tomato, and lentil mixture. Stir in the chopped fresh cilantro an mix well.
Pour the dressing over the lentil and tuna salad and season with pepper to taste.