I haven't tried this recipe yet, I just wanted to copy it down and make sure I saved it for use later. Hopefully I don't need to make any changes at all... I copied it straight from this page: http://chowhound.chow.com/topics/48418

HOME MADE VEGETARIAN FISH SAUCE: So, I've noticed that a lot of asian dishes call for fish sauce, and if you're a true vegetarian like me you always feel like that puts the recipe just out of reach. I've come up with my own vegetarian fish sauce and I think it's 99% close the real thing.

I based the main part of it off the Wikipedia Vegetarian Fish Sauce recipe, but I felt the recipe there lacked a few things which put it into the realm of "tastes like the real thing" but it's 100% VEGETARIAN.

HOW TO MAKE VEGGIE FISH SAUCE
INGREDIENTS
2 - cups shredded dried seaweed
4 - cups water
3 - cloves garlic (smashed but not minced)
1 & 1/2 - Tbsp whole black peppercorns
1/2 - cup soy sauce
2 - tsp lime juice (concentrate OK)
2 - tsp lemon juice (concentrate OK)
2 - Tbs vinegar
3 - tsp sugar
1 - tsp ground ginger
1 - tsp ground garlic
1/4 - tsp chili powder

You can find the dried seaweed at just about any asian market. Personally I prefer the type that shredded kinda small versus the large sheets of seaweed. I think that when it's shredded it makes for a richer sauce.

HOW TO PREPARE VEGETARIAN FISH SAUCE
1. In a large bowl, add 2 cups dried seaweed + 4 cups water
2. Bring to a boil, then reduce heat and simmer for 20 minutes
3. Add garlic cloves + peppercorns + soy sauce + lime juice + lime juice
+ vinegar + sugar + ginger + garlic powder + ginger + chili powder
4. Bring to a boil, turn heat down to medium and cook for 30 minutes
5. You can adjust the salt level by adding water
6. Allow to cool
7. Strain into a container

Straining it is the key. Once it's strained you can funnel it into a large water bottle, and label it "Veggie Fish Sauce" or as it's called in Vietnam "Nuoc Mam Chay" If you've ever tasted the real fish sauce (in your pre-veggie days) you can sample a tiny bit and see just how close to the real thing it really tastes. But caution...this stuff is stinky and strong! Just like the real fish sauce.

Hope you like it.
Ms Nadja Dee Witherbee
Seattle WA