Tomatoes with peaches, grapes, feta and oregano

Ingredients

• 4 tbsp olive oil
• 1 tbsp red or white wine vinegar or cider vinegar
• ½ small red onion or 1 shallot, very finely sliced
• 2 peaches, stoned and chopped into 2-3cm pieces
• 200g red grapes, halved
• 600g tomatoes, chopped into 2-3cm pieces
• ½ bunch oregano or marjoram, leaves picked
• 50g feta, crumbled
• 50g kalamata olives, pitted and roughly chopped