Strawberry jam with rhubarb

Ingredients:

• 5 cups chopped rhubarb (about 10 12-inch stalks)
• 3 cups hulled strawberries, quartered (about 450g)
• 2.5 cups of sugar
• Zest of 1 lemon + 2 tbsp. l. lemon juice

Preparation:

1. Combine the rhubarb, strawberries, sugar, lemon zest and juice, and 3/4 teaspoon salt in a large saucepan. Mash gently to release some of the berry juices. Set aside for 10 minutes to allow the sugar to dissolve. Meanwhile, place a small plate in the freezer to chill; you'll need it to test the jam for doneness.
2. Place the pan over medium-high heat (add black pepper). Bring to a boil, then reduce the heat to medium and simmer, stirring frequently, until the jam thickens, about 1.5 hours. To check for doneness, drop a small amount of jam onto a chilled plate and freeze for 2 minutes. Run your finger or a spoon through the jam. If it retains its shape and consistency, remove from the heat. If it's runny, continue simmering and check again in 5 minutes.
3. Once the jam reaches the desired consistency, pour it into jars and let it cool completely before using. Seal the lids tightly. The jam can be stored in the refrigerator for up to 6 months.
   
   For taste you can add:
   1) 1 tsp freshly ground black pepper before putting the jam on the fire;
   2) scraped out seeds and vanilla pod (remove the pod from the jam before putting it into jars) or 2 tsp vanilla paste;
   3) 2 tbsp balsamic vinegar just before removing the jam from the heat.