In a large skillet, heat the coconut/olive oil over medium to medium high heat. Sprinkle the pork on all sides generously with salt and pepper and then with the cumin powder. Use your fingers to rub the cumin into the pork loin. Sear the cumin spiced pork in the hot coconut oil for about 3 minutes per side or until the pork is nice and brown all the way around. Move the pork from the skillet to the slow cooker and top with the sliced onions and mushrooms. In the same pan that you seared the pork in, add the salsa, strained tomatoes, the 1 tablespoon of cumin, and garlic, and whisk together until bubbly. Taste and season with salt and pepper if desired. Pour the sauce over the pork, onions, and mushrooms in the slow cooker and cook on high for 5-6 hours or on low for 7-8 hours.