Salmon Fillet with Vinaigrette

WHAT YOU'LL NEED

• 1 Knorr Fish Stock Cube
• 4 tbsp olive oil
• 4 salmon fillets
• 1 tbsp white wine vinegar
• 1 tsp caster sugar
• 2 red onions, finely chopped
• 150 g cherry tomatoes, halved
• 1/2 tbsp tarragon, chopped
• 1/2 tbsp chives
• 1/2 tbsp basil, chopped