The most important step in making soup is taking the time to properly build and layer flavors, so really give the onions and garlic adequate time to cook here. Be careful--hot liquids can expand and explode in the blender or food processor, so be sure to cool the liquid, and don't fill the blender too full! In pro kitchens, everything sweats--not just the chefs, but the vegetables, too! "Sweating" is kitchen speak for cooking vegetables and aromatics in fat over low to medium heat to extract their flavor without achieving color. Be sure to season the vegetables and aromatics first, because the salt draws out the juices you need for sweating to happen.