For the red curry paste:
Combine all the ingredients in a food processor or blender, and puree until smooth. Add more coconut milk if the paste is too thick to puree.
This will yield more than you will need for one batch of sauce, but can be refrigerated for up to 2 weeks.
For the steak:
Season the steak with the garlic, cumin, oil, salt and pepper. Let the meat rest at room temperature for about 45 minutes. This will give the salt and spices time to penetrate the meat, and will also help the meat to cook more evenly.
Grill the meat for about 4 minutes on each side for medium-rare. Let the meat rest for about 5 to 10 minutes under a loose foil cover. This will allow time for the juices to redistribute throughout the steak, so you won’t lose all that goodness when you slice it.
For the sauce:
Whisk the curry paste into the skyr in small batches, tasting as you go, until you’ve reached your desired curry strength. Season with salt.
To serve, spoon the sauce over the steak. This recipe is great by itself, or sliced and thrown in a pita with fresh veggies. It also pairs excellently with grilled watermelon.