turmeric. I had to ask because I thought maybe it was saffron, which also turns veggies a yellow color. Some information about turmeric from Wikipedia:
Turmeric is widely used as a spice in South Asian and Middle Eastern cooking. In Nepal, turmeric is widely grown and is extensively used in almost every vegetable and meat dish in the country for its color, as well as for its medicinal value. In South Africa, turmeric is traditionally used to give boiled white rice a golden color.This food is served on teff, a strange spongy kind of bread, and the whole meal has become my favorite food at the market. It turns out that teff is a kind of wheat widely cultivated in Ethiopia and Australia. We don't seem to grow it much here, but traditionally Ethiopian food is served with the bread, which is torn off and used as a kind of edible utensil. I use a regular fork, though. You can see the teff bread behind the closed container.