Rotonda Red Eggplant

Melanzana Rossa di Rotonda is a protected designation of origin, granted by the European Union in 2010. It covers fruit grown in four communes in the province of Potenza, Basilicata (Rotonda, Viggianello, Castelluccio Superiore and Castelluccio Inferiore) in the Mercure valley inside Pollino National Park.

The botany matters, because it explains everything else. This is not the aubergine sold everywhere else. The common eggplant is Solanum melongena; this is Solanum aethiopicum, a separate African species of the gilo group, related to the aubergine roughly the way a tomato is related to a potato.

The fruit is round or slightly flattened, five to eight centimetres across, fifty to a hundred and fifty grams, with deep ribs running down from the stem. It turns from green to orange to full red as it ripens, and anyone seeing it for the first time takes it for a beefsteak tomato. Growers stopped correcting the mistake years ago.

Inside, the flesh is firm and cream-green, with seeds held in distinct chambers like a tomato rather than scattered through the flesh like an aubergine. The flavour is the real surprise: peppery-hot, with a clean bitter finish and an almost metallic edge closer to raw artichoke than to anything in the nightshade family. There is none of the sweet sponginess of a roasted aubergine. Local cooking has always treated it accordingly: blanched in vinegar and packed under oil, not grilled and dressed.

Hot, bitter and firm. The heat is a slow diffuse pepperiness, more like a radish or a turnip top than a chilli, and it builds rather than hits. Behind it comes a clear bitterness with a mineral, artichoke-like edge that stays in the mouth.

Texture is the other departure. Where a normal aubergine collapses and drinks oil, this one holds its shape, browns at the edges and stays almost crisp. Sliced thin and raw it eats like a firm, bitter salad vegetable.

Preserved in oil, the way most people meet it, the vinegar blanching rounds off the aggression and leaves something between a pickled artichoke heart and a mild giardiniera.

Cut off the calyx with a knife every time: the spines on the green cap are real and sharp. Do not salt the fruit first: salting is the trick for removing bitterness from a common aubergine, and here the bitterness is the reason you bought it.

The simplest treatment is the best. Slice a centimetre thick, cook in a hot pan with olive oil, a crushed garlic clove and a chilli, five or six minutes a side. It will not soak up the oil and it will not collapse. Finish off the heat with a few drops of wine vinegar: the acidity is what balances the bitter edge.

Stuffed is the celebration version. Hollow the fruit leaving half a centimetre of flesh, fill with breadcrumbs, aged pecorino, garlic, parsley and, if you like, minced pork, sit them in a dish with a finger of water and bake forty minutes at 180 C.

Preserved in oil is how you will meet it outside Basilicata. Serve at room temperature, never fridge-cold, drained and given ten minutes to breathe: on bread with an aged sheep's cheese, in a sandwich with salami, or on an antipasto plate. Less obvious and very good: sliced paper-thin raw, dressed with olive oil, salt and oregano the way you would treat a raw artichoke.

Fresh fruit is much firmer than a common aubergine and keeps accordingly: a week or two in a cool larder at 8 to 10°C, spread out rather than piled. A cold fridge works against it, because solanaceous fruit held much below 5°C develops chilling injury, with pitting and browning appearing on the skin within a few days. It also carries on ripening after picking, so the colour deepens from orange towards red, the flesh softens, the seeds harden and darken, and the bitterness intensifies. As it loses water through the skin the ribs sharpen and the surface wrinkles. Stringing the fruit up to hang is the traditional local method.

Jars in oil or vinegar sit in a dark cupboard until the producer date. Once opened they go in the fridge, and the practical point is to keep the pieces pushed under the liquid with a clean fork, since anything standing proud of the surface dries out and darkens. Oil clouds and thickens when cold and clears again at room temperature. Fresh fruit collapses if frozen raw, so grill or blanch it first, after which it holds around six months.

Nothing about it looks like an aubergine. It is round, five to eight centimetres across, ribbed like a small tomato, with a green calyx, and it turns from green through orange to bright scarlet as it ripens on the plant. Cut it open and the flesh is pale cream green, denser and firmer than a common aubergine, packed with small seeds, and the taste is bitter with a real peppery bite. Botanically it is Solanum aethiopicum rather than Solanum melongena, which is why it behaves so differently. The fresh season runs August to November around Rotonda, in the Pollino.

At a glance people take it for a tomato or a persimmon. The genuine relative is the gilo or jilo sold in African and Brazilian shops, the same species picked green and used differently. Thai eggplants are round but green and white streaked, and the ornamental Solanum integrifolium sold as pumpkin on a stick is a decoration. Most of what leaves Basilicata is jarred in oil or vinegar under the DOP mark. Fresh fruit is 4 to 8 euro a kilo locally; a 300g jar runs 7 to 12 euro.

Fresh fruit essentially never leaves Basilicata. Total production is a few dozen hectares, harvested by hand over four months, and it is consumed locally or preserved. Do not expect to find it fresh in the US or the UK at any price.

What travels is the jar. Italian specialist importers and online food shops carry Melanzana Rossa di Rotonda DOP in oil in 280 to 300 gram jars; in the US expect 18 to 30 dollars per pound of drained product, in the UK 35 to 55 pounds per kilo. In Italy the same jar runs 8 to 14 euro, and fresh fruit at markets in the Pollino costs 4 to 8 euro per kilo in season.

Read the label rather than the picture. The words Melanzana Rossa di Rotonda DOP must appear in full, with the EU mark, the packer's name and a lot number. Jars labelled only 'red eggplants in oil' are unregulated and may be the same species grown anywhere, or ordinary aubergine coloured by the preserving liquid.

If the fresh vegetable is what you want, look for jiló in Brazilian groceries or garden eggs in West African shops: same species, different selection, a fraction of the price.

Rotonda itself, in the province of Potenza, where a festival in mid-August serves the vegetable grilled, stuffed, preserved, baked into a parmigiana and, for anyone who wants to measure how far it is from an aubergine, raw in a salad.

The Mercure valley around it is the rest of the trip: Viggianello, Castelluccio Superiore and Inferiore, Terranova di Pollino, Episcopia. This is the Lucanian side of Pollino National Park, the largest in Italy, and thirty kilometres of mountain road here earn their keep on scenery alone.

September and October are the right months: the plants carry flowers and fruit at every stage of ripening at once, and restaurants put the vegetable on the menu fresh rather than out of a jar. August has the festival but most of the crop is still orange. Matera, two hours east, is the practical base for anyone not driving into the mountains: shops in the old town sell the DOP preserve alongside crusco peppers and the local bread.