In a large skillet, combine the chicharrones and water and cook over moderately high heat, stirring, until the chicharrones start to soften and the water is absorbed, 3 to 5 minutes. Add the salsa verde and cook over moderate heat, stirring, until the chicharrones are coated and the salsa is thick, about 5 minutes. Season with salt. Serve in the corn tortillas, topped with sour cream, purslane and crushed chicharrones.