The Katie Stewart cookbook I used for the banana loaf yesterday was still open on my dining table this morning and glancing through it, I decided to use her recipe for ‘tuna in a fennel marinade’ for this evening’s meal. It was nice and easy to put together at lunchtime and would comfortably fit within the ‘at least 4 hours’ suggestion for how long the tuna should be marinaded.

I like to eat fish – especially the kind like tuna and salmon that are rich in healthy omega oils – at least a couple of times a week. I think tuna is best marinaded before griddling – my usual form of cooking the fish – and I often serve it with some kind of salsa, like mango. It’s a strong flavoured, meaty fish and can easily take a robust marinade. I like to cook it on a hot griddle very quickly so the outside is nicely done but the inside still pink, indeed, almost raw. It’s a fish that is easily overcooked and it’s important to have everything else ready before you cook it and then eat it straight away. Tuna cooked too much will become dry and unpleasant. Fresh tuna, well cooked, is a revelation if you’ve been used to eating it out of tins; an entirely different species. Not that I’m against tins and always keep some in my cupboard for a quick sandwich or salad, but a lovely fresh tuna steak is the real thing!

The recipe was in the ‘Barbecue’ section of Entertaining with Katie Stewart, so ideally suited to griddling. First of all though, get the marinade ready well ahead of the time you want to eat.

I had to make some adjustments to measurements as I was only cooking one piece of tuna and the recipe was for six! However, I kept as close as I could to Katie’s recipe. Get a dish and put in 2 tablespoons mild oil (I used mild olive but rapeseed or sunflower is good too), the zest of half a lemon; the juice of half a lemon; 1 dessertspoon fennel seeds, 1 heaped tablespoon freshly chopped parsley, 1 crushed clove of garlic and some salt and pepper. Whisk all together with a fork and then add the tuna steak. Slide is around in the marinade a bit to cover one side and then turn over before you cover in cling film and put in the fridge for about 4 hours.

I had half a large fennel bulb in my fridge and decided to pick up on the fennel theme by doing a fennel gratin. I cut the fennel into wedges, boiled in salted water until just tender, drained and then put in a small ovenproof dish. I grated over Parmesan and dotted with butter, then put the oven for about 20 minutes till nice and brown. I also roasted some potatoes, cut into small pieces, parboiled in salted water, drained and then coated in olive oil. I sprinkled over some lovely Ottolenghi Lebanese za’atar which with its thyme and sesame seed flavourings is great on roast potatoes.

I also briefly boiled some sugar snap peas in salted water – just for a couple of minutes so they retained their lovely bright green colour and a good ‘snap’. Then the tuna: get a griddle nice and hot, lift the tuna steak from the marinade and cook for just a couple of minutes on each side – though this depends on your thickness of your tuna. You can actually see the ‘cooking’ rising at the side and you should get a nice browning.

As it was cooking, I tipped the remaining small amount of marinade into a small saucepan and boiled up and reduced, ready to pour over the tuna steak when I served it. I lay the vegetables out on a plate and as soon as the tuna was ready, transferred to the plate, poured over the hot marinade – and ate straight away!

The tuna was still nicely pink in the middle, so gorgeously moist. The marinade added a strong and wonderful flavour to it: the garlicky-lemon taste with a spicy aniseed taste from the fennel seeds. It was gorgeous! Really good. And so simple. The preparation took hardly any time at all and I’m sure if you didn’t have 4 hours to leave the steak in the marinade but just half an hour or so, it would still be worth doing. Great recipe!