Testing - Beet soup

http://www.canadianliving.com/food/beet_soup.php

I made this for a group of 12 young people (20-30 age group) and they loved it. I'll have to make it again for a, perhaps, more experienced and discerning group to get the feedback I need to develop a recipe. I used cumin, added a 1/2 cup of milk , and served it with a dollop of sour cream.
1 - Mixed reactions - E. felt it needed to be thicker; B. thought it was too 'earthy'. I thought is was just right, but wondered if I'd forgotten to add the cumin because I couldn't taste it. I did not add all the stock. The total liquid I added was 6 cups instead of the recommended 12. On second thought, I think there has been a typo in the original and it should be only 4 cups of one of 3 possible types of stock. I shall make a selection and change my version. So there!

2 teaspoons vegetable oil
2 onions chopped
2 cloves of garlic minced
1 potato
4 cups (1lb?) chopped beets
4 cups beef, chicken, or vegetable stock
4 cups chicken stock
4 cups vegetable stock
1/2 cup milk
2 teaspoons curry paste
2 teaspoons ground ginger
2 teaspoons cumin
Sour Cream

1. In saucepan, heat oil over medium heat. Add onions, garlic, potato and cumin. Cook, stirring often, for 5 minutes or until onions are softened.
2. Add beets and stock; bring to boil. Reduce heat to medium-low; cover and simmer for 20 minutes.
3. Puree soup until smooth. If desired, thin with more water, stock or milk. Season with salt and pepper to taste.