Cook potatoes in a large saucepan of boiling, salted water for 15 minutes or until tender. Drain. Cool. Peel and chop.
Meanwhile, heat a large nonstick frying pan over high heat. Add bacon and brown onion. Cook for 2 to 3 minutes or until brown onion has softened. Transfer to a large bowl. Add potato and egg. Combine mayonnaise and vinegar in a bowl. Add to potato mixture. Season with salt and pepper. Toss to combine.
Serve topped with gherkins and green shallot. Serve.
