Aubergines are really a fruit - important to know so you don't store them in the fridge. Photograph: iStock

One of the advantages to being a blow-in to Ireland with a funny-sounding accent is that it frees me to ask dumb questions. Baffled by so many unfamiliar foods — fish varieties, types of potatoes, cuts of bacon — when I spot a fellow shopper who seems to know what they’re doing, I ask.

“Ah, the poor wee dote,” I can see them think. “Doesn’t know his hake from his plaice.”

Occasionally, I get a chance to return the favour. I was picking up vegetables to make a big pot of ratatouille the other day when another shopper pointed at my bag of aubergines. “What are you going to do with those?”

If they were hoping for a quick escape, they came to the wrong fella. Aubergines are one of my favourite vegetables of summer. Get me started and I can talk for Ireland about them.

I spared them the part of my lecture about aubergines really being a tropical fruit (only important because you should store them at room temperature rather than in the fridge). And I skimmed lightly over the incredible range of varieties, from the familiar black bowling balls to tiny green ones that look like peas.

I did show them how to choose one: pick out the aubergines that are rock-hard, so they almost feel like they’re bursting from the skin.

And I gave them a quick talk about salting. Many recipes reflexively call for salting aubergine before cooking. To determine whether this complication is necessary, I once spent a week experimenting and, to my taste, salting only makes a difference if you’re going to fry them. Steamed, broiled, grilled, baked, I couldn’t really tell the difference.

Fried, though, I found salting before cooking turned the finished aubergine from somewhat spongy to rich and creamy. But this is not a step you can shortcut. To make a difference, you really need to let the aubergine stand salted for at least an hour, better an hour and a half.

I explained that to prepare aubergine this way, cut it into pieces and put it in a colander. Sprinkle liberally with salt, toss to coat evenly, and set it to drain over a bowl. You’ll be surprised how much liquid will be expressed. After it’s done, rinse the aubergine chunks under running water and pat thoroughly dry.

But since aubergine is somewhat unfamiliar to you, I told them helpfully, you might like a simpler introduction. You can’t beat grilling. Slice it about 3cm thick (you can do this crosswise, but lengthwise will give you more uniform portions). Brush the slices with garlic-infused olive oil and grill over medium heat. Turn fairly frequently to prevent scorching.

When the aubergine is a lovely golden brown, remove it to a platter, brush with a little more of the oil, scatter over fresh thyme, basil or oregano and sprinkle lightly with a little red wine vinegar. This is good right away, but any leftovers will store in the refrigerator for a few days, ready when you want them.

You can elaborate this any number of ways, I explained. I sometimes make a kind of Georgian pesto by crushing walnuts and coriander in a mortar and pestle and thinning it with olive oil. These grilled aubergines are also good simply coarsely pureed and spread on toast, topped with chopped tomato and maybe some pecorino or ricotta.

I could sense that I was losing my friend, so, building quickly to a climax, I told them that for me, the queen of aubergine dishes is ratatouille, that summer stew with peppers, courgettes and tomatoes — basically everything that makes the season special.

Too often, despite the brilliant ingredients, ratatouille can turn into an indifferent muddle. The way I cook it avoids that. I wish I could remember where I learned it so I could give sufficient credit, because it is one of my favourite dishes. The big difference in my ratatouille is that rather than stewing everything together, I cook each vegetable individually, then bring them together to warm briefly. It’s a bit fiddly, but this way each vegetable keeps more of its own character.

It’s really more a technique than a specific recipe. Base the balance of ingredients on what looks best at the market rather than on any Platonic ratio.

Start by sauteing a base of sliced onions and red peppers. When they’ve softened, season with salt and some herbs (thyme, oregano, basil, maybe some crushed fennel seeds) and, of course, garlic. Tip this into a large stewpot with a slotted spoon, leaving as much of the oil as you can in the frying pan. Cook chopped courgette in the same pan and when it is softened, add it to the stewpot.

Now cook the salted, rinsed and dried aubergine chunks. When they have softened and collapsed, add finely chopped tomatoes or passata and season with red wine vinegar. Cook just until the vinegar has lost its raw smell, then tip it into the stewpot, along with whatever oil remains in the frying pan.

You can let this simmer over very low heat until you’re ready to serve, or if it’s more convenient you can prepare it a day ahead and keep it in the refrigerator. It’s at least as good the second day as it is the first.

And, as far as I’m concerned, if it’s a warm day, ratatouille may be even better served cold or at room temperature. On blistering days (rare in Ireland, common in California), we often make a dinner of nothing more than cold ratatouille served with fresh mozzarella or burrata. And, of course, a glass of crisp, chilled rosé.

“And so, in conclusion ...” I said, but when I looked up, my new friend had fled.