Add all the vinaigrette ingredients into a food processor and blend until combined. You can keep this a little chunky if desired or blend until smooth!
Slice or dice tomato and avocado as desired. I like to do a large dice so there is plenty of surface area for the vinaigrette but the presentation of sliced tomatoes and avocado is also really lovely.
Spoon the scallion vinaigrette over the tomatoes and avocado and give them a gentle toss. Then add to serving bowl or assemble onto a serving platter and let sit at room temperature until ready to serve*
*feel free to make this salad an hour or two in advance. the longer it sits, the more all the flavors will come together. do note, that after 4 hours or so you may see the avocado start to brown so if you plan to eat this after that time, you will want to cover in an airtight container and refrigerate.