Based on Tuscan fagioli e tonno, the flavour of this easy, delicious salad is enhanced by marinating the cannellini beans in a warm dressing until you're ready to assemble and serve.
Try to use the best quality tuna in olive oil you can - that sold in jars is usually excellent.
In a large microwave safe bowl, whisk together the extra virgin olive oil, red wine vinegar, a large pinch of salt, a good grind of black pepper.
Stir in the sliced onion, chopped fennel or celery if using, the chopped garlic, and the drained cannellini beans.
Microwave on high for approximately 2 minutes or until the beans and dressing are warm: heat in 30 second bursts, stirring between each burst.
Stir in the lemon zest, 2 tbsp of the juice, and HALF the chopped parsley. Set aside until cooled to room temperature.
Although now ready to eat, it's better to set aside to improve the flavour. Store in an airtight container in the fridge for 30 minutes or up to 24 hours. Bring back to room temperature before serving.
Stir the beans then taste. If needed, add more lemon juice, salt or pepper. Stir in the remaining parsley.
Spread the rocket or other salad leaves on a platter or individual plates.
Spoon the beans over the rocket then top with the tuna broken into large chunks.
Drizzle any remaining dressing all over the salad and serve with the optional garlic toasts.