Preparation Time:20 minutes + leave 2 hours to set
Cooking Time:few minutes
Level of Difficulty:Easy
Servings:6-8

Ingredients

• 1 red onion  
• 1 tablespoon dried oregano  
• black pepper  
• 1 tablespoon red wine vinegar  
• 200ml extra virgin olive oil  
• 5 good tomatoes  
• 1 teaspoon caster sugar  
• pinch of Maldon salt  
• 1 very large cos lettuce  
• 1 bulb fennel  
• 125g pitted black olives  
• 400g feta cheese  
• juice of half a lemon 

Method

1. 1. Peel and finely slice the red onion then sprinkle over the oregano and grind over some pepper. 
2. 2. Pour in the vinegar and oil and toss well, cover with clingfilm and leave to steep for a good 2 hours; longer’s fine. What you’ll notice, once it’s had its time, as well, is that the blooded crimson of the onion is somehow now a luminescent puce. It’s a science thing, something to do with the acid in the vinegar: don’t ask. You don’t need to be fully conversant with the technicalities to be able to take advantage of them. That’s to say, I often use this trick in other ways. An otherwise overwhelmingly brown slab of meat can be immediately lifted (in looks and taste) by being covered with some red onions, cut into wedges of 8 or so, and then fried in olive oil, to which, once softened, you add the juice of a lemon. 
3. 3. On top of the lemony pink onions add some sprinkled Maldon salt and a generous amount of summer-green chopped parsley. Or make a quick sauce for pasta (this should be enough for a 500g packet of spaghetti) by cutting a red onion into very fine half-moons (ie, cut the onion in half and then slice each half as finely as you can), frying it in olive oil, spritzing in the juice of half a lemon, as before, and then tossing this, along with 200g tuna cut into thin little rags, into the cooked drained spaghetti; the heat of the pasta will cook the raw tuna plenty. 
4. 4. Add seasoning to taste, and some extra virgin olive oil as you like, and a goodish amount of chopped fresh parsley (again). But these are just suggestions: the pink onion technique can be drawn on in whatever way pleases you. 
5. 5. But to return to the case in hand: when you want to eat, get started with the rest of the salad. Cut the tomatoes into quarters, then cut each quarter into quarters (always lengthwise) again, so that you have a collection of very fine segments (rather than chunks). Sprinkle the sugar and a pinch of salt over them and leave while you get on with the rest. 
6. 6. Wash the lettuce if you need to (I always try and get away with not) tear into big pieces and put into a large, wide salad bowl. 
7. 7. Slice the fennel and add that, then the olives and the feta, cut or crumbled into rough chunks, and toss well. 
8. 8. Now add the tomatoes, the red onion – now lucidly pink – in its marinade-dressing and the lemon juice. Toss gently, but thoroughly, so that everything is well combined. This is addictive: you will find yourself making it all through summer – and beyond.