Generously season lamb cubes with salt. Add grapeseed oil to pot and swirl to coat. Add lamb, in batches so as not to overcrowd pot, and sear until golden, turning once, about 5 minutes per side. Remove lamb to a large plate as they finish.
Drain all but 1 tablespoon oil (or add an additional tablespoon if pan is dry). Add onion, ginger, garlic cloves, and chile de arbol, season with salt, and saute until golden in spots, about 5 minutes. Add lamb back to pan. Create a well in the center, add one additional tablespoon grapeseed oil, and add spices. Stir to coat with oil and toast until fragrant, 30 seconds. Gently fold to incorporate lamb and onions. Sprinkle with cornstarch and sugar, stir to combine, and add water, scraping bottom of pan to deglaze. (You can also do this in a skillet on the stovetop over high heat; cooking time will be reduced. Transfer mixture to Instant Pot and proceed as per recipe.).
Cover and cook on high pressure for 25 minutes. Release the pressure naturally.
With a slotted spoon, remove lamb and aromatics to a bowl. Cover to keep warm. Skim fat from cooking liquid, using a fat separator, if desired. Season cooking liquid and lamb with salt. Return lamb and aromatics to cooking liquid, stir to combine, and serve over rice, garnished with cilantro.