Tuna Tomato Cucumber Tramezzini

Ingredients

• 160 g (1x 5oz can tuna)
• 1 garlic clove
• 1/2 shallot or 1/4 onion
• 1 tsp wholegrain mustard
• 1 tsp capers
• 1 parsley sprig
• 1/2 tsp lemon juice
• 1 tbsp butter
• 1 tbsp olive oil
• 1 tbsp sour cream
• 2 long Tramezzini bread slices or 8 slices white toast
• 1 small cucumber
• 1 large tomato