Put the onions in a bowl. Cut up one tomato. Scoop out the seeds and liquid with your fingers. You don’t want all that moisture to make your toast soggy. Chop the tomatoes up small. Put that into the same bowl. I’m using 2 green chiles chopped, you can use less or more according to your taste. Add the chiles to the bowl. Add ½ tsp salt, you don’t want to add too much salt because the cheese is already salty.