Grilled cheese sandwich with pickled Spanish onion - 9Kitchen

Ingredients

• 8 slices sourdough bread
• 100 gm butter, softened
• 120 gm soft goat's cheese
• 180 gm each Gruyère and Tilsit, finely grated
• 120 ml red wine vinegar
• 2 tbsp caster sugar
• 2 Spanish onions, finely shaved
• 1 tbsp coriander seeds, dry roasted and coarsely crushed