1. Macerate the Fruit:
   • In a large glass bowl, combine 2 pounds chopped rhubarb, 1 pound chopped strawberries, and 2½ cups granulated sugar. Stir thoroughly to coat.
   • Cover with plastic wrap and refrigerate for 12-24 hours to let the fruit release its juices.
   • Tip: Stir once during maceration to ensure sugar dissolves; longer maceration (up to 24 hours) deepens flavor.
2. Prepare for Canning:
   • Remove fruit mixture from the refrigerator and stir in the seeds from 1 scraped vanilla bean pod.
   • Wash 6-8 half-pint jars, lids, and bands in hot, soapy water; rinse well.
   • Place jars in a water bath canner with the wire rack, cover with water, and bring to a simmer (180°F) to keep hot. Place lids in a small saucepan of warm (not boiling) water to soften seals.
   • Place a small plate in the freezer for testing the jam’s set later.
   • Tip: Keep jars hot to prevent cracking when filled with hot jam; don’t boil lids, as it can damage seals.
3. Cook the Jam:
   • Transfer the fruit mixture (with juices) to a large heavy-bottomed pot (e.g., 5.5-quart Dutch oven). Add 3 tablespoons bottled lemon juice and ¼ teaspoon fine salt.
   • Bring to a boil over medium-high heat, stirring occasionally to prevent sticking.
   • Once boiling, the mixture will foam. Reduce heat slightly to medium and stir every few minutes as it simmers rapidly, evaporating liquid and thickening (10-15 minutes).
   • Tip: Skim heavy foam if desired for clearer jam, but some foam is normal; watch heat to avoid scorching.
4. Test for Set (22-25 Minutes):
   • As the jam thickens (around 22-25 minutes), stir frequently, scraping sides to prevent burning. The fruit will break down, and the mixture will become cohesive.
   • Check temperature (optional): Aim for ~212°F for a thick set.
   • Test set: Spoon a small amount of jam onto the chilled plate, tilt vertically, and observe the flow. It should descend slowly, not run quickly. Alternatively, let it sit on the plate for 30 seconds, then push with a finger or spoon; it should crease and not flood back together.
   • If not set, cook 2-5 minutes more and retest. Cooking time varies based on fruit moisture (wetter fruit takes longer).
   • Tip: Jam will thicken further as it cools; avoid overcooking to prevent a rubbery texture.
5. Fill the Jars:
   • Remove hot jars from the canner using a jar lifter and place on a kitchen towel.
   • Ladle hot jam into jars, leaving ¼-inch headspace. Use a non-metallic spatula or bubble remover to release air bubbles.
   • Wipe jar rims with a clean, damp cloth to ensure a good seal.
   • Place lids on jars and screw on bands until fingertip-tight (not overly tight).
   • Tip: Work quickly to keep jam and jars hot; measure headspace with a ruler or canning tool for accuracy.
6. Process the Jars:
   • Return filled jars to the canner, ensuring they’re covered by at least 1 inch of water.
   • Cover the canner, bring to a rolling boil, and process for 10 minutes (adjust for altitude: add 1 minute per 1,000 feet above sea level).
   • Turn off heat and let jars sit in the canner for 5 minutes to stabilize.
   • Tip: Start timing when water reaches a full boil; ensure jars remain upright during processing.
7. Cool and Store:
   • Remove jars using a jar lifter and place on a kitchen towel on the counter, spacing them apart to cool.
   • Let cool undisturbed for 12-24 hours. Check seals: Lids should be concave and not flex when pressed.
   • Store sealed jars in a cool, dark place for up to 1 year. Refrigerate unsealed jars and use within 3 weeks.
   • Tip: Label jars with the date and contents; listen for the “ping” as lids seal during cooling.

Cooking Tips:

• Prevent Burning: Stir frequently, especially as jam thickens, and use a heavy-bottomed pot for even heat.
• Test Early: Start checking the set at 20 minutes to avoid overcooking, as fruit moisture varies.
• Altitude Adjustments: Check your altitude and adjust processing time to ensure safe canning (e.g., 15 minutes at 5,000 feet).