We always use apples after washing so there's no need to wash the peels. However, if you haven't washed apples before use, wash the peels now.
Remove the seeds from the cores of apples.
Put the peels and cores in a pot. Add water up to the level peels and cores and completely covered.
Let the water boil first on high flame and when it begins to boil, lower the heat and cover the pot with a lid.
Let the peels and cores cook for about 20 minutes or until they turn soft and mushy.
Switch off the flame and mash them with potato masher.
Take another bowl, place a strainer on it and transfer all the cooked/mashed material onto the strainer.
Press the mushy material with a spoon to get maximum liquid out.
Transfer the liquid collected back to the pan and place on flame.
Add sugar and let mixture boil for about 20-30 minutes on medium heat until the liquid looses its flowing consistency and becomes little thick like a sugar syrup.
To check the doneness, coat a spoon into the liquid and draw a line at the back side of spoon with a finger. If the clear line is drawn, your liquid has attained the correct consistency.
Add citric acid/tatri and mix it well.
Let the mixture turn completely cool on room temperature.
Transfer to an airtight container and place it refrigerator.
Your Apple peel and core jelly is ready.