When I went to Thailand and had this soup for the first time I think my whole world just flipped right over on me all at once--it was the most remarkable taste experience ever. The flavors just blew me away--piquant, sour, spicy, rich, amazing! You have to try it. And you can easily make either Tom Yam or Tom Ka with a simple substitution. This soup is simple to make, but what's tricky is having the ingredients on hand. Because I love this so much, I stockpile fish sauce, coconut milk and dried shiitake mushrooms. My hubby grows lemongrass in the garden year-round, and we have a lime tree that contributes a leaf here and there. You can make this without lime leaf and lemongrass, but add some lime zest to substitute. I think you are going to love this special and wonderful soup--one of the great wonders of the culinary world!