Roast beef sandwich

Slices wholegrain loaf - 2Roast beef - 3.5ozBalsamic onions - 1ozHorseradish spread - 0.5ozRocket - 0.5ozHorseradish spreadMix together 2oz horseradish sauce and 10oz sour creamBalsamic onionsRed onions (peeled and sliced 1/4 inch) - 80oz Balsamic vinegar - 24oz Olive oil - 8ozMaldon sea salt - 0.5ozFresh ground black pepper - 0.5ozTo prepareMix the onions with the other ingredients in a bowl. Spread evenly on a tray and bake in a pre-heated oven at 160ºC for 20-25 minutes, tossing occasionallyTo assemble the sandwichSpread horseradish mixture on both slices. On one slice place roast beef, onions and rocket. Place the other slice of bread on top and cut in half diagonally.