This is the closest recipe to what I use all the time. I don't measure, but proportionally, this looks right to me. Looking at your picture, I like to leave my tomatoes a bit chunkier. I generally leave out the jalapeno altogether, and sometimes add some fresh ground pepper and a little olive oil, but this is optional. To make guacamole, I just stir a few spoonfuls of this into a mashed avocado. It's like getting two dips for the effort of one! Perfect on plain cheese quesadillas.
I made this, with a few alterations (DH and DF are very spice-phobic) for last night's NYE dinner party. I used 8 roma tomatoes (because hothouse were over 2x the price per pound and don't pack the flavor punch of romas. I diced a bell pepper in place of the jalapeno and half a red onion in place of the small onion. It ended up making close to a quart (thank goodness because DH was hungry when we got home from work yesterday afternoon and we kinda attacked it). My mom LOVES pico, and this is the closest recipe I know of to one from Nicky's, a local Mexican restaurant chain. Needless to say, this is a keeper!