In a large skillet, heat the olive oil. Add the potatoes and cook over moderately high heat, stirring occasionally, until browned, about 10 minutes. Reduce the heat to moderate and cook the potatoes until tender, about 5 minutes. Add the shallot and cook until softened, about 3 minutes. Add the spinach and stir until just wilted, about 1 minute. Season with salt and pepper and serve.