The object of the onion and garlic in the pan with the butter is to 'sweat' the aromatics. This is just another fancy pants cooking term for cooking them on medium-low heat until they are soft and not browning at all. The sweating time is a great time to add some salt and pepper. The salt will help to draw some of the moisture out of the onions and garlic (making the softening happen faster) and the pepper will become tastier with the low heat. This process should take about 10 minutes or so, depending on the freshness of your onions and garlic. This tip is a little late but... when cutting onions you should stick them in the fridge for at least 30 minutes before you start your slicing. The onion releases and enzyme when you cut into it that becomes a gas and reacts with the water in your eyes causing the tears and discomfort. If you chill your onions the enzyme becomes less reactive. I use this method all the time and it really works!!
The amount of liquid that needs to be added depends on the amount that is released by your zucchini. Add enough that it just barely covers your sweaty veggies. I keep using the term liquid because its totally up to you what you add. I added water with some powdered chicken bouillon. You can add low sodium chicken stock or, if you are of the vegetarian persuasion, add some low sodium veggie stock. The low sodium stock allows you to control the saltiness of your soup. This option is key for those of you with Happy Partners with less than perfect blood pressure :)
Soup done!!! I would suggest serving this yummy soup with some toasted, garlic rubbed crusty bread and a dollop of sour cream or a tablespoon of heavy cream plopped in the middle!! The one additional step you could take would be to strain your soup. You would only need to take this step if you used an older zucchini. If you take a look a the finished product picture at the top you can see some white flecks in the soup. These are the pieces of seed that didn't break down during the blending process (not a problem with younger fruits). The bits didn't bother the HH and certainly didn't bother me so I left them for some added texture. I froze most of the soup in individual servings for taking to lunch at the office when in cools off later in the year. I hope you enjoy the soup! The zucchini are still pouring out of the garden so be ready for some more garden creations!