CORN TORTILLAS: Heat a dry cast-iron skillet over medium heat until hot but not smoking. Cook 1 raw 5 1⁄2" tortilla at a time, turning once, until blistered and charred in spots, 1 1⁄2–2 minutes per side. As tortillas are cooked, wrap in a clean dish towel to keep warm.
TORTILLA CHIPS: Quarter 10 cooked corn tortillas (see above). Working in batches, deep-fry wedges in 350° oil, stirring frequently, until golden and crisp, 2 1⁄2–3 minutes. Drain on paper towels and season generously with salt while still hot and slightly moist.
PUFFY TACO SHELLS: For each shell, deep-fry 1 raw 4 1⁄4" tortilla disk in 350° oil, using tongs to keep it submerged and to fold in half so edges are about 2" apart. Fry until it holds its shape; stir in oil until blistered, about 3 minutes total. Drain on paper towels.
CRISPY TACO SHELLS: Warm a dry cast-iron skillet over medium-low heat. For each shell, cook 1 raw 5 1⁄2" tortilla, turning often, until leathery, 2–3 minutes per side. Deep-fry in 350° oil, shaping with tongs to fold in half so edges are about 2" apart, until crisp, 2–3 minutes. Drain on paper towels.