Make sure the cauliflower is completely dry, then chop into large pieces; you can include the core, but discard the leaves.
Put the cauliflower pieces in a food processor with the cumin, paprika and cayenne; pulse everything together until it is the texture of rice. Work in batches if necessary and don't over process or it will get mushy.
In a large skillet, heat the oil over medium heat. Add the garlic and shallot and cook until softened, 2 to 3 minutes. Add the cauliflower mixture and cook until heated through, 3 to 5 minutes. Transfer to a serving dish and toss in the scallions and cilantro. Season with salt and pepper and add a squeeze of lime juice to help remove any bitterness from the cauliflower. Serve warm.