First heat a large pot of water to boiling. Have another bowl of cold water with ice set to the side. Remove the stem area and slice a small X in the bottom of each tomato.

Blanch the tomatoes in the boiling water for 30-45 seconds, until you see the skin beginning to peel off. Remove to the cold water.

Repeat until you’ve blanched all the tomatoes. Then peel off the skins.

Cut a whole onion in half, and the half you plan to use, remove any papery skin but leave the onion intact so it’s all one big piece (if it falls into two pieces over time, that’s fine). Peel the skin from the orange. I use a potato peeler to do this and it works well. You’re looking to get big, long pieces of orange skin, but not much of the white pith underneath. A little bit is OK, but aim to get mostly the orange skin and not the white pith as it can be a little bitter. Give the tomatoes a rough chop or blend for a couple seconds in a blender.

In a large pot combine the tomatoes, onion, and orange skins. Season with just a little salt and pepper, but don’t go crazy as we’ll add more later. Cook over low/medium heat for 1 hour to 1 hour 15 minutes. The tomatoes will break down and much of the liquid will reduce.

Remove the onion and orange skin pieces from the pot. Add the juice from half the orange (about 2 tablespoons). Taste and add salt and pepper plus a big pinch of cayenne.

Serve this over pasta, gnocchi, or use as pizza sauce. You can refrigerate anything you don’t use that day in an airtight container for up to three days. If you plan to store this for longer, I would freeze in a ziplock bag or other airtight container.