Feel free to use a couple of tins of beans if it's more convenient.
Tinned beans aren't bad these days – they have got much better for some
reason. But if you're using dried, which still taste better, soak them
overnight in water. They'll double in size. You then just need to drain
them and put them into a pan with fresh water to cover. Bring to the
boil, then simmer them for around 40 minutes or until tender –
sometimes I put a squashed tomato and a potato in the water with them,
as it helps to soften the skins. When done, drain them, discarding the
tomato and potato, and put them into a large bowl with 8 tablespoons of
peppery olive oil, the red onion, anchovies and chillies. Season with
salt and pepper and the lemon juice – for a bit of a twang.
Preheat your griddle pan until really hot. Season the tuna steaks with
salt and pepper, sprinkle over the lemon zest and pat a little olive
oil on both sides. Sear the steaks for a minute on each side. While the
fish is searing, get your guests round the table. Throw the herbs into
the dressed beans, mix up and divide between the plates. Take the tuna
off the heat, tear it up and place on top of the warm beans. Nice with
some cold white wine.