Homemade Playdough and a fun new Ikea product!

My kids love squishing their hands into homemade playdough and I love the time they spend whipping up their creations!  The easiest recipe I've found is below.  I attempted to make green and purple batches ... the purple turned into a lovely shade of wet cement  ... oh well.  They still loved it!
Oh, and the fun mat beneath the playdough?  I scored that at Ikea!  It's non-stick and cleans up beautifully.  One side has fun illustrations for the kids, and the other has metric conversions for the grownups:)
The recipe:
1/2 cup salt
1 cup water
2 TBsp cream of tartar
1 cup flour
1 TBsp vegetable oil
Food coloring
Mix the flour, salt, cream of tartar, and the oil into a saucepan.  Add the water.  Cook on medium heat for 3-5 minutes, stirring well.  The mixture will start to get dough-y, and will naturally form into a ball in the center of the pan.  At that point, remove from heat and dump onto your countertop.  I wait a few minutes until it's cool enough to handle, then separate into batches and dye with the food coloring.  You will knead the color into the warm dough.
Store in an airtight container or a plastic Ziploc bag.