Cut the potatoes into large chunks, leaving the skin on. Add to a large saucepan of boiling water and cook for 15-20 minutes, until tender. Drain and transfer potatoes to a large bowl.
Stir the olive oil and vinegar through the hot potatoes. Add the lentils, olives, capers, garlic, parsley, spring onions and lemon juice. Season with a pinch of salt and a good grinding of black pepper. Toss well to combine and serve warm.
Per serving: 435 calories, 7 g protein, 11 g fat (2 g saturated fat), 27 g carbohydrate (2 g sugars), 4 g fibre, 510 mg sodium