Drain the olives and but them in a bowl.
Cut the chilli in half, remove & discard the seeds, stem and veins. Chop the flesh, add these to the olives.
Finely chop the garlic, onion and red pepper, add these to the olives, together with the oregano.
Add the vinegar, lemon juice and olive oil.
Cut the gherkins into thin slices and add these to the olives. Season to taste with salt and ground peppercorn.
Mix well and transfer the olives and the marinade into a sterilized jar, then seal.
Marinate in the fridge for at least 2 hours, preferably overnight. Keep chilled after opening.