There was some mention of making sugar and syrup using something other than Maple sap in the other thread. I know I have a link somewhere for making sugar and starch at the same time from sweet potatoes. Looking for it now...

SWEET POTATO STARCH

HOUSEHOLD METHOD

This is very easily made, all that is necessary is to grate the potato, the finer the better, put into a cheese cloth or thin muslin bag and dip up and down, in a vessel of water, squeezing occasionally, continue washing as long as the washings are very milky.

Allow it to settle five or six hours or until the water becomes clear, pour off; rewash the starch, which will be in the bottom of the vessel, stir up well, allow to settle again, pour off the water and let dry, keep the same as any ordinary starch.

USES

Use exactly the same as cornstarch in cooking.

SWEET POTATO SUGAR

By saving the water which the pulp was washed in first, in the starch making process and boiling down, the same as for any syrup, a very palatable, non-crystalline sugar will be the result; this sugar or syrup can be used in many ways.

Have you tried this? 
Does the sweet potato starch impart a flavor on the thickened product?

Yes, I tried it so I can have that skill should I need it. The starch is just starchy, the sugar-water does have some taste and color from the sw pot but when evaporated turns browner and thicker.
I forgot to say this was a cut-and-paste from an old article from the Texas A&M website about George Washington Carver's work with, among other plants, the sweet potato.

I'm living in Latvia and corn does not do well here, so potato starch is the standard here.

Sorry Rockguy, but I can't agree! In recipes, the potato starch performs exactly as corn starch and the taste is no more noticeable than would be the case with corn starch.

We make potato pancakes (for those not familiar with potato pancakes, just think hash browns) about twice a month and, as a by product, we end up with enough potato starch for (virtually) all our needs.

After the potatoes are grated, as much moisture as possible has to be squeezed out as possible. This requires quite a bit of hand strength. If you leave too much starch in, the pancakes are rubbery.

The squeezed liquid is sieved or run through cheesecloth to remove any leftover pieces of potato and allowed to settle. The liquid on top will oxidize brown.  The liquid is poured off and several changes of fresh water added until it stays clear, allowing the starch to settle between each change.

When the water doesn't discolor anymore, the starch is placed on a paper sheet to dry.

Spock, we are talking about Sweet Potato, an Ipomea, not the Irish potato. The process is about the same and would work for many vegetables that have both sugar and starch in the roots.