In a large pot, stir together the flour, salt, and cream of tartar.
Add in the water and oil.
If you're only making a batch of one color, you can add in the food coloring now.
Cook over medium heat, stirring continuously. Continue to stir until the dough begins to form into a ball.
Remove the pot from heat and place onto wax paper.
Allow the dough to cool a bit and then knead until it is smooth.
If you plan on making multiple colors, now is the time to divide the dough into balls. Place in separate bowls, or into ziplock bags if you don't want to stain your hands!
Add 5-6 drops of food coloring, kneading the dough until the color is all mixed in. Add more food coloring for a brighter color.
Store in an airtight container.