Make your dressing in a small bowl by combining olive oil, dijon mustard, lemon juice and salt + pepper.
Remove the bones from your sardines and place in a separate bowl with your tuna. Be gentle when breaking it apart so it doesn’t turn mushy!
Add raisins, chopped peppers, lemon zest, chopped dill, and a good bit of cracked pepper to your tinned fish.
Pour your dressing over fish and give it a taste to adjust for seasonings like more salt and pepper or another squeeze of lemon.
Make your salad topping by combining arugula and julienned watermelon radishes with a dash of olive oil and a pinch of salt.
Finally, make your dijonaise by combining equal parts mayo and dijon mustard.
Slather your toasted bread with dijonnaise, then tuna salad, and finally your arugula salad.