Sri Lankan  Seeni Sambol (Spicy Caramelized Onion Chutney)

Ingredients

• 1 lb red onion, thinly sliced
• 1 small cinnamon stick
• 4 green cardamom pods
• 1 tablespoon sugar
• 2 tablespoon oil
• 2 tablespoons tamarind juice or 1 teaspoon tamarind paste
• 5 curry leaves
• A drop of vanilla extract or a 2-inch pandan leaf
• 1 tablespoon of spicy red chili pepper flakes
• Salt to taste