wow, that's really strange. Long ago i made a historical/trad. recipe of Irish Moss (= agar agar) Pudding (w/ agar agar that i gathered ,myself, from the beach), milk, honey, citrus zest. Panna cotta by any other name. It had no sea smell and was lovely. Every time i see agar agar on the beach, i think of that pudding!

Just want to pipe and to day that my agar agar was neither tasteless nor odorless, being vaguely redolent of the sea—which didn't do much for the green grape gelatin I was making, though it would work fine for chawan mushi. Be careful!

Agar is your best option, especially if you are new to vegan/vegetarian baking. It is tasteless, odorless, and completely natural. If you buy agar powder, the ratio is about 1/2 tsp per cup of liquid, depending on the brand. I use Telephone brand, available at Southeast Asian and Chinese markets, and find that I can get away with slightly less than that.

With agar powder, a little goes a long way. On the other hand, if you are using agar flakes, you will have to add a higher ratio per cup of liquid. I don't know the exact proportions because I don't use it. Even though agar flakes are less processed and therefore more natural, they take much longer to dissolve in liquid, and sometimes result in a chunky texture. You can avoid this by grinding it in your blender, but you will still have to add whatever measurement is recommended on the package.

Other vegan gelatin alternatives include water chestnut flour and arrowroot starch :) Once you get the hang of things, you could experiment and see which texture you like best. They are all a little different, but agar is the easiest to work with.

You might want to make a small amount to see how the agar sets up in your recipe.

I'm not a vegan and quite honestly I've never heard of panna cota (I've googled it now - thanks for the food lesson!) but Mary Jane Butters makes what she calls a "Chill-over powder" with is a vegan, organic version of gelatin. I've used other products from her and found her products to be excellent. Check it out http://shop.maryjanesfarm.org/store/p/65-ChillOver-Powder.aspx
Good Luck!

Definitely go with the agar agar. I used it to make a vegan version of a pumpkin pie, and it worked out quite well. Here is a good substitution info site, on the page for gelatins. It does take the agar agar (I have flakes) a while to dissolve. http://www.foodsubs.com/ThickenGelatins.html

That's not in my wheelhouse but until someone else comes along, google 'vegan panna cotta' there are lots of blogs on the topic. You have to be sparring with the agar agar, it seems. Here a very useful thread on chowhound with a report of success using kosher vegetarian gelatin substitute called Kojel
http://chowhound.chow.com/topics/605840