Rinse and dry pork shoulder, then place it in the slow cooker.
Peel garlic and slice red onion; scatter atop roast.
Grind peppercorns; dust roast with salt, pepper, cumin, and oregano.
Zest and juice grapefruit, lemons, limes, and 2 blood oranges.
Add zest and juices to roast; add flesh of blood oranges.
Place lid on the slow cooker, and cook on low for 8-10 hours.
After cooking, remove the bones and reserve for bone broth. Shred the meat, if desired.
Serve with avocado, red sauerkraut, and microgreens.