In a medium bowl, comine the warm milk, sugar, salt, and vegetable oil. Stir until the sugar has dissolved.
Add the yeast. Mix well, and let sit until the yeast has dissolved.
Add the sifted flour to the wet ingredients and stir until well-combined. Cover the bowl and let sit for 30 minutes in a warm spot to rise.
Preheat a griddle to 300 degrees Fahrenheit (150 degrees Celsius), or medium heat. Place mason jar rings onto griddle. Spray each ring with pan spray and dust each ring with a sprinkle of cornmeal.
Using a #20 ice cream scoop, place 2 scoops of batter into each ring. The #20 scoop is equivalent to 3 1/2 tablespoons, so each ring should be filled with about 7 tablespoons of batter. Gently smooth the batter out to cover the inside of each ring.
Place an inverted sheet pan over the rings and cook for 5-6 minutes, or until golden brown. The pan should not rest on the rings. There should be clearance for the muffins to rise; otherwise, the muffins may stick to the pan and force the dough to spill over the edge.
Remove the sheet pan and sprinkle cornmeal onto the muffins, then use tongs to flip the rings and the muffins. Cover again with the sheet pan and cook for another 4-5 minutes, or until golden brown.
Place the muffins on a wire rack to cool and carefully remove the mason jar bands. Allow muffins to cool.
To serve, split with a fork and toast to your liking. Top with butter, jam, and your other favorite breakfast condiments.
These mason jar english muffins will keep at room temperature for 2-3 days, and longer in the refrigerator.
