Grilled Cheese with Seeni Sambol Onions – Duke's Mayo

Ingredients

• 2 tbsp. coconut oil or neutral oil
• 1 medium red onion, thinly sliced into half-moons
• ½ tsp. kosher salt
• Black pepper, to taste
• ½ tsp. crushed red pepper
• 1 tbsp. tamarind concentrate
• ½ cup Duke’s Mayonnaise, plus more for brushing bread
• 2 cups (8 oz.) shredded low-moisture mozzarella cheese
• ½ cup (2 oz.) shredded sharp white cheddar cheese
• ⅔ cup finely chopped red onion (from about half a small red onion)
• 1 serrano chile, stemmed, seeded, and finely chopped
• 1 tsp. kosher salt
• 8 slices white sandwich bread
• ½ cup seeni sambol onions (see recipe)