To make your oregano oil, pound the oregano with a good pinch of sea salt in a pestle and mortar until you have a paste. Add the lemon juice and 4 tablespoons of olive oil and stir until you have a good drizzling consistency.
Bring a large pan of water to the boil, add your peas and cook for 3 to 4 minutes, then remove them with a slotted spoon or sieve. Add the broad beans to the pan and cook for 3 to 4 minutes, depending on their size. Drain and leave to cool, then pinch the skins off any big beans (you can leave the skin on any small or medium ones).
To dress the peas and beans you want the same balance of acid and oil as you would have in a salad dressing. So, put the olive oil and a good pinch of salt and pepper into a large bowl. Chop up most of the mint and throw it in, add the peas and beans and mix everything around. Add lemon juice to taste. You can serve the dressed peas and beans hot or at room temperature.
Heat a griddle pan or barbecue until hot, season your tuna steaks with salt and pepper and pat with some of the oregano oil. Place in the pan and sear for 1 to 2 minutes on each side. Personally, I like to keep my tuna a little pink in the middle as this tastes much nicer, but if you’re going to cook it through please don’t nuke it.
Tear the tuna into 2 or 3 pieces and toss in a large bowl with the rest of the oregano oil. This will give you a lovely combination of flavours. Serve the fish immediately with the peas and broad beans scattered with the rest of the mint leaves.
P.S. Sometimes I love to throw random delicate greens like baby spinach, watercress, even rocket, in with the broad beans for 30 seconds before you drain them. The combination of peppery irony greens, creamy broad beans and sweet little peas makes the veg taste even better.