Prepare your peaches by blanching them in boiling water for 30-60 seconds, then transferring them to an ice bath using a slotted spoon. This will make the skins slip right off. Cut them into cubes.
Dice your red bell peppers and yellow onion into small, even pieces, about the same size as your peach cubes for consistent texture.
Finely mince the garlic, fresh ginger, and hot pepper. If you like your salsa extra spicy, leave the seeds in; if you want milder heat, remove them.
In a large stockpot, combine all the peaches, bell peppers, onion, garlic, ginger, hot pepper, red pepper flakes, brown sugar, and apple cider vinegar. Stir well to combine.
Bring the mixture to a boil over medium-high heat, stirring occasionally. Once it reaches a rolling boil, reduce to a simmer and let it cook for 15 minutes. Stir often to prevent sticking and to make sure the flavors meld beautifully.
While the salsa simmers, sterilize your jars and snap lids in a large pot of boiling water or a dishwasher on the sterilize setting.
Remove the jars from the hot water bath using a jar lifter, and place them on a clean tea towel on your counter.
Use a ladle and jar funnel to fill the hot jars with salsa, leaving about ½ inch headspace at the top. Gently tap the jars or use a non-metallic utensil to remove any air bubbles. Wipe the rims clean with a damp tea towel to ensure a proper seal.
Place the sterilized snap lids on top, screw on the bands fingertip-tight, and process the jars in a boiling water bath for 20 minutes. Make sure the water covers the jars.
Carefully remove the jars with your canning jar lifter and set them on a towel to cool completely. Once cool, check that the lids have sealed by pressing the center; it should not flex. Place jars in a cool dark area to store.