Bring a few inches of water to boil in a large pot. Place the potatoes in a steamer basket and sprinkle with 1 teaspoon of the salt and cook until tender, about 20-30 minutes.
While the potatoes are cooking, heat the ghee and olive oil over low heat in a large skillet. Add the onion and cook for about 3 minutes. Add the cauliflower florets, stir to coat and cook for an additional 6-8 minutes.
Stir in the cumin seeds, curry powder, turmeric, and cayenne pepper. Sauté for one minute, then stir in the tomatoes, water, and the other teaspoon of salt. Remove from heat, stir in the coconut milk and blend with an immersion blender. You may need to transfer to a bowl depending on the size of your skillet, if so, return to the skillet when complete.
When the curry is back in the pan, add the tempeh and bring to a simmer. Cook for 5 minutes and add the steamed potatoes. Sprinkle with cilantro. We love this served with cauliflower rice!