Heat the vegetable oil or bacon grease in a heavy-bottomed skillet over medium-high heat until shimmering but not smoking.
In a medium bowl, stir together the yellow cornmeal and salt until evenly combined.
Carefully pour the boiling water into the cornmeal mixture, stirring constantly until you form a thick, sticky dough.
If the dough is too dry, add 1 tablespoon more hot water; if too wet, add 1 tablespoon more cornmeal.
With clean hands, scoop about ¼ cup of dough and flatten into a ½-inch-thick patty. Repeat with remaining dough.
Place patties into the hot skillet without overcrowding and fry 3–5 minutes per side, until golden brown and crispy.
Transfer cooked cornbread to a paper-towel–lined plate to drain any excess oil.
Serve immediately while warm and crispy.