Gina Ruiz of Doña Lupe's Kitchen makes Chia Fresca the authentic way, she adds chia gel to limeade. Here's the link to her recipe for this, and other traditional Mexican agua frescas.
Agua de Chia – Chia Seed Water
1 cup chia seeds (you can find these in the Mexican spices section of your supermarket, usually in a little pouch)
1/2 cup fresh squeezed lemon juice
Sugar to taste
2 quarts of water
Soak the chia seeds in two cups of water for 2-3 hours until they are soft and gooey. Chia seeds have a lot of gooey almost gelatinous goop on them when they are soaked. That’s part of the fun. Think Boba in a very tiny form.
In a large glass jar or pitcher add the 2 quarts of water, the lemon juice and the now spongy, wet chia seeds. Stir well and add sugar to taste and plenty of ice. Before serving make sure to stir it well so that the chia seeds are floating throughout the whole jar.