Cut the apples into 1-inch pieces without peeling or coring, but discard any damaged or spoiled spots.
Place the apples in a large nonreactive pot and pour in 8 cups of water. Bring to a boil over medium-high heat. Lower heat to maintain a simmer and cook without stirring until the apples soften, 35 to 40 minutes (sometimes less).
Remove from the heat. Set a fine-mesh sieve lined with cheesecloth over another large pot, and pour the apple-water mix into the sieve. Try not to press on the apples so that the jelly does not become cloudy. You should end up with about 7 cups of juice. The NYT recipe notes that some apples can take hours to strain, but mine did not! If it does take awhile to strain the apples you can place the sieve and pot in the refrigerator.
Place a small plate in the freezer to use for testing the setting point of the jelly. Set the pot with the juice over medium-high heat. Add the sugar and lemon juice, and stir until the sugar is dissolved. Bring to a boil, skimming and discarding any foam that rises to the surface.
Reduce the heat to medium and simmer until the liquid reduces by about three-quarters and a candy or deep-fry thermometer registers 225 degrees. This will take about 40-50 minutes, occasionally longer. To test for doneness, spoon a small amount of liquid onto the cold plate from the freezer and return to the freezer to cool completely, about 2 minutes. Drag a spoon through the jelly. The setting point has been reached if it wrinkles and the wrinkles hold their shape. If they don’t, continue to cook the jelly and test every few minutes on the cold plate.
Once the jelly is done cooking, add the salt and stir to dissolve. Ladle the hot liquid into clean, sanitized jars, screw on the lids, and follow the steps to can your jelly, or allow to cool to room temperature and store in the refrigerator for up to 4 weeks.
Try different apples. You can use any kind of apple you like to make apple jelly! I typically make apple jelly with our homegrown Gravenstein apples but you could use another type of apple. A sweeter apple will produce a sweeter jelly.
Make it with honey. If you wish to make this jelly refined sugar-free, you could experiment with using honey instead of sugar. You may find you want to reduce the amount of honey because it is naturally quite sweet.
Try this method to make pear jelly. You can substitute pears for the apples and follow the method outlined above!
Can or make fridge jelly. You can easily keep this jelly in the fridge and enjoy it without needing to can it. However, I love taking an extra step and canning preserves! If you have never canned preserves before, the USDA guide is a great place to start.