In a double boiler, heat the soy milk until it just begins to simmer. You want it to be warm/hot, but not boiling. Little bubbles of soy milk forming on the sides of the pan are what to look for for the next step.
Add the salt and give a good stir to dissolve.
Remove pan from heat, and add the lemon juice. Stir just enough to get the lemon juice distributed.
You should see some clumping in the soy milk. That's good! That's what we want to see. Let the mixture cool.
Line a collander with cheese cloth (don't skimp on the cheese cloth. I tried a plastic mesh strainer and the holes were too big! you can buy the cheese cloth at any grocery store). You want to have enough of the cheesecloth hanging over the edge of the collander to grab and tie for aging the soy cheese. Put the collander in the sink and pour/scrape all the soy milk curds into the collander.
Let it sit like that until the soy milk "whey" drains. (you could use the "whey" for noodles, pastas, soups, or whatever if you don't want to throw it away -- )
Take the cheesecloth out of collander and bring all the edges together, with the lump of soy ricotta in the middle. Tie the cheesecloth with a string and hang the cheese so that it continues to drain. Don't squeeze it -- let gravity and a little time do the work for you.
When it stops dripping, open the cheese cloth and transfer the ricotta to a covered container. Refrigerate and use as you would use ricotta cheese.
NOTE: When I made this, I used the vanilla flavored soy milk. I think it gave the ricotta product more of that sweet cream taste, and I think I'd rather have that than the straight soy flavor.
NOTE: If you wanted to flavor this, with garlic powder or herbs, do it when the milk is in the saucepan. You can add sun dried tomatos and such after the cheese has been strained, but it gives a different texture and presentation with chunky sized add ons later.