Steak Sandwich

Ingredients

• 1 8oz fillet steak
• 2 tbsp dijon mustard
• A handful of watercress
• 1 tbsp mayonnaise
• 1 ciabatta loaf
• 1 red onion, cut into 3-4 rounds
• 1 tsp sherry vinegar
• 1 tsp soft brown sugar
• A pinch of sea salt
• 1 bay leaf
• 5 cherry tomatoes
• 1/2 tsp smoked paprika
• 1 sprig rosemary