Put a few small plates in the freezer as you'll use them to test the marmalade later.
Using a vegetable peeler, remove the zest in strips from oranges. Cut strips into 1-by-1/8 inch strips. With a knife, cut off all white membrane, or pith, from peeled oranges. Discard the pith.
Working with one piece at a time, set fruit on its cut end and use a sharp knife to remove the white pith from the outside. Be as precise as possible—you really don't want any of the pith left on the fruit, as it’s super bitter. Discard the pith.
Hold the peeled fruit over large bowl to catch the juice and hold with one hand. Then use a sharp paring knife to cut out the sections, letting the sections drop into the bowl below. Pick out the seeds and set them aside. You'll actually use them later.
Once you've cut the sections out of the fruit, you'll be left with a handful of the membrane that separates the orange sections. Over the bowl with squeeze out as the remaining juice into the bowl with the orange sections. Discard the membranes. Again, do not throw away the seeds.
Fill the instant pot with 2 cups of water. Set your instant pot to ‘saute’ on ‘more’ and bring to a boil. Once boiling, add the zest and continue boiling for 10 minutes. Drain the water from the pot, leaving the zest and then fill the pot with 2 cups of water again. Again, set the timer for 10 minutes (it's okay that it hasn't begun to boil yet when you start the time) and bring to a boil over high heat. One last time drain the water from the pot while leaving the zest and fill with 2 cups water, boil for another 10 minutes. Drain one last time while leaving the zest.
Next add the fruit and juices to the zest in the pot along with 4 cups of water and honey. Stir to dissolve the honey and bring everything to a boil, about 10 minutes.
While the orange mixture is heating up, make the ‘pectin bag.’ Put the membranes and seeds in a double-layer of cheesecloth. Lay a large layer of cheesecloth in a medium plate or bowl and add the membranes and seeds on top. Tie the ends of the cheesecloth together so the membranes and seeds are held inside. You’re essentially making a teabag out of the cheesecloth or a ‘pectin bag.’
Once the orange mixture starts to boil, add the "pectin bag" to the mix. Let cook for about 1 1/2 to 2 hours while stirring occasionally.
For the final marmalade to set, it needs to be 220 F for at least 5 minutes. You can use a candy thermometer, but if you don't have one, you will need to do several tests using those frozen plates. If you’re not using a candy thermometer, make sure to watch it as it thickens. It’s easy to get distracted and forget about it.
After the marmalade has reached 220 F and stayed there for 5 minutes, you test the marmalade by dropping a spoonful of the mixture on one of the chilled plates you set in the freezer earlier. Let it sit for a minute, swirl the plate to spread the marmalade, then drag your finger through the mixture. If the marmalade is ready, it will leave a clean track behind it. The mixture will have also reduced and be thicker than water. When you hold your spoon up, you will notice that the liquid doesn’t roll off the spoon as quickly. You don’t want it to look like super thicker and already look like marmalade as it will continue to thicken as it cools. If it’s already super thick then it was end up hardening as it cools and won’t spread.
Once it has finished cooking, remove the pectin bag from the marmalade. Use a large spoon to press the bag against the side of the pot to get as much of the marmalade out of the bag as possible. Discard the bag and its contents.
Remove the pot from the heat and let the marmalade mixture sit for about 5-10 minutes before transferring it to the jars. You’ll want it to cool slightly before transferring it to jars.