Instructions

1. In a large bowl, combine the peaches, sugar, lemon juice, and cardamom seeds. Cover and let sit at room temperature for 2 hours. Pour contents into a colander set over a 6-qt. saucepan. Let the mixture drain for a few minutes to release the syrup, then stir to release more. Transfer the colander to another bowl to capture any remaining syrup.
2. Bring syrup to a boil in the saucepan over high heat; attach a candy thermometer to the side of the pan and cook, stirring constantly, until mixture reaches 220°, about 8 minutes. Add peaches and any accumulated juices into the syrup. Continue to cook until the fruit no longer floats and is dispersed evenly throughout the gel, 8-10 minutes. Remove from the heat and stir in rye until incorporated, followed by the butter.
3. Meanwhile, submerge four 1-cup canning jars, along with their lids and ring bands, in a large pot of boiling water and sterilize over high heat for 10 minutes. Transfer sterilized jars, lids, and bands to a clean dish towel. Fill each jar with hot jelly, leaving at least 1⁄4" of space at the top. Wipe jar rims with a clean dish towel, place lids on jars, and secure ring bands.
4. Transfer filled jars to a canning rack; place rack in a pot of gently boiling water so that jars are submerged by at least 1"; let boil for 10 minutes. Transfer jars, set at least 1" apart, to a dish towel and let cool, undisturbed, for 24 hours. To test that jars have properly sealed, unscrew bands and lift each jar by the edge of the lid; if the lid holds, the jar is sealed. If it loosens, jar is not fully sealed, and jam should be refrigerated and used within 2 weeks. Sealed jars will keep, in a cool, dark place, for up to a year.Ladle jam into four, clean 8-ounce jars, leaving a 1⁄2” headspace. Clean the rim of the jar with a damp cloth, place the lids and rings on the jars, and process in a boiling water bath for 10 minutes. Cool completely and check the seals on each jar. Store in a dark, cool location for up to one year.