Caramelize the onions. Heat a pan over medium heat and add a teaspoon of oil and then the diced onion. Cook for about 6-8 minutes, undisturbed until there are brown crispy edges to most of the onions. Stir them, then add a bit of water and turn the heat down to medium-low. Continue cooking until the water cooks away and then continue the process of stirring and adding water when the pan looks dry, and then cooking it away for about 20-30 minutes – or until the onions look nice and brown and caramelized to your preference. I like to cook mine for an hour for sweeter onions.
Let the onions cool.
Mix the rest of the ingredients together in a medium bowl.
Add the onions and mix well.
Taste and then season with salt and pepper. Garnish with green onions and serve.