Apple Cheddar Vegan Grilled Cheese Sandwich

Ingredients

• 2 tbsp extra virgin olive oil
• 1/2 onion, julienned
• 1 tsp salt
• 1 cup thinly sliced green apple
• 4 slices sourdough bread
• 2 tbsp butter
• 2 tbsp vegan mayonnaise
• 2 tsp Dijon mustard
• 2 tbsp grated vegan parmesan
• 4 slices vegan provolone cheese
• 1 cup shredded vegan cheddar cheese