2 to 3 medium lemons
3 C. granulated sugar
1/4 C. crystallized ginger, chopped
1/3 C. slivered almonds, toasted and coarsely chopped (see note)
Place rhubarb slices in a wide, heavy 5- or 6-quart saucepan. Zest the lemons to make 3 T.; add to the pot. Squeeze 2 lemons to make 6 T. juice; add to the pot. Mix in the sugar and ginger. Let the pot stand for 3 hours or until sugar is dissolved. Wash 3 half-pint jars and fill with hot water until needed. Prepare lids as manufacturer directs. Stir rhubarb mixture thoroughly, then place pot over medium-high heat and bring the mixture to a boil, stirring often. Cook 10 to 15 minutes, stirring often, until a thermometer reads 220 degrees or the mixture passes the cold saucer test (see note). Remove from heat and stir in the nuts. Drain the jars. Ladle hot jam into 1 hot jar at a time, leaving 1/4-inch head space. Wipe the jar rim with a clean, damp cloth. Attach the lid. Fill and close the remaining jars. Cool until the lids pop, a few hours, then refrigerate for up to 2 months, or freeze for 1 year. For longer storage, process in a boiling-water canner for 10 minutes (15 minutes at 1,000 to 6,000 feet; 20 minutes above 6,000 feet). Note: To toast nuts, heat in a dry skillet over medium heat until they start to brown. Stir occasionally. Be careful not to scorch them. Note: To test for doneness use the cold saucer test. To do a test, remove pan from heat and place a spoonful of hot jam on a chilled plate. Place in freezer for 1 minute; draw finger through jam on saucer. If jam does not flow back and fill in path, it is thick enough.