Spicy Tuna Melt Sandwich - Daily Hlib

Ingredients

• 2 cans (5 oz each) tuna in water, drained
• 1/3 cup mayonnaise
• 1 tablespoon sriracha or hot sauce
• 1 tablespoon Dijon mustard
• 1 celery stalk, finely chopped
• 1 small red onion, finely chopped
• 1 tablespoon fresh parsley, chopped
• Salt and black pepper to taste
• 8 slices sourdough bread
• 2 tablespoons unsalted butter, softened
• 1 cup shredded cheddar cheese
• 1 medium tomato, thinly sliced