Place 6 wooden skewers in a container and cover with cold water. Let sit until ready to use.
Place potatoes in a medium pot and fill with water. Set over medium-high heat and bring to a rolling boil. Cook for 9-11 minutes, until knife tender but not falling apart (You don't want them breaking apart when you skewer them). Drain and let sit until room temperature.
In a medium bowl, combine the curry powder, ½ tsp of the garlic powder (double this if doubling the recipe, then save remaining for later use), cayenne pepper, garam masala, 2 tablespoons avocado oil, (double the avocado oil if doubling the recipe), and freshly ground black pepper. (TIP: Don’t add salt since the halloumi is already very salty).
Add the halloumi cubes and gently coat, making sure not to break or damage the cubes. Let sit until ready to grill (If longer than 1 hour, cover with plastic and refrigerate).
When ready to grill, preheat an outdoor grill to medium-high heat (you can also use a grill pan, greasing with oil and cooking over medium-high heat). TIP: It helps to grease the grill with oil before cooking so the skewers don't stick.
Place potatoes and tomatoes in a medium bowl and toss with a drizzle of avocado oil, a good pinch of Kosher salt and freshly ground black pepper, and the remaining garlic powder.
In a small bowl, combine the red onion, cilantro, and a pinch of Kosher salt and freshly ground black pepper.
Grill the skewers on all sides until the halloumi is nicely charred with grill marks, 5-7 minutes.
Serve immediately on a platter atop the Curried Yogurt. Sprinkle with the red onion mixture.