Saucy Punjabi Potatoes (Kase Wale Aloo)

Once again, I followed the recipe except for the Thai chiles--hot enough for me without them. I did add some finely chopped raw spinach. I thought the cooking time, especially on high, was a bit too long, but the result is delicious, though the long cook time meant I had to add some more water--in fact, it was not soupy at all. I tasted it before adding the optional yogurt and didn't care for it, but after the addition of the salt, cilantro and yogurt, however, it was really good. I don't think the yogurt should be optional.