This is just a basic tomato salsa. The real secret to making a good fresh salsa that is not runny is to add some canned tomato sauce to it. I like to add the El Pato brand because it has a good spicy flavor.
If you can't find El Pato you could add some chili powder. These are just guidelines as to how much of each thing to put in it all depends on your taste. I like to use Roma tomatoes because they have more tomato and less seeds ect. I use the blade chopper on my food processor and it makes this really easy, you could also chop everything. Canned tomatoes will work too.
10-12 Roma tomatoes
2 Bell peppers, any color
2 Yellow onions
2 Jalapenos, more or less depending on your taste
2 small cans tomato sauce or El Pato
Salt and pepper to taste
Chop everything and add tomato sauce. It usually tastes better the next day when the flavors can blend together.