Remove the stems from the tomatoes.
Plunge the tomatoes into a pan or bowl of boiling water for 10-15 seconds, then remove them and cool briefly under cold water. Peel off the skin.
Halve the peeled tomatoes, scoop out the seeds and cut into strips.
Drain the capers and mash together with the olives.
Cut 2 x 30cm square pieces of foil and brush 1 tsp olive oil on each.
Place the chicken breast fillet on the foil squares and season with salt and pepper.
Spread the tomatoes, capers and olives on the chicken fillets and season again with salt and pepper.
Wash the oregano, shake dry and scatter the leaves over the chicken. Scrunch up the foil to enclose the chicken, leaving a small opening at the top.
Pour the white wine into the parcels through the opening.
Scrunch the packets closed and place on a baking tray. Cook in a preheated oven at 200°C (180°C fan, gas 6).