Plum Strawberry Jam recipe
Four jars – about 1 cup (250ml) each.
Sometimes smooth jam is preferred while other times, it’s nice to find lumps of fruit suspended in the jar.
For this jam, I kept the fruit a bit chunky, using an immersion blender to partially puree the fruits.
You can leave the fruits relatively chunky, or puree them until smooth. If using a traditional blender, I recommend cooling the fruit puree down to room temperature first.
Never fill the blender more than half full of with hot liquid as the steam can force the hot fruit out of the top. (Draping a kitchen towel over the top provides extra insurance.)
You can also use a food mill, food processor, or go low-tech with a potato masher for the fruit.
Some people like vanilla in their jam.
If you’re one of them, you could add half a vanilla bean, split lengthwise, to the fruit after it’s pureed.
I’m often asked if you can reduce sugar in jam.
Sugar is both a preserving agent and helps with jelling.
My jams use less sugar than the traditional 1:1 ratio.
If you want to use less sugar, it will be looser and won’t keep as long.
You can find recipes online for microwave or freezer jam that would fit that bill, including recipes that use alternative sweeteners.
I store my jams in the refrigerator and find they will keep for six months to one year.
If you want to can them, you can find information about doing that here.
I usually do the wrinkle test to check if the jam is done.
If using a candy thermometer, most jams set at between 218-220ºF (103-104ºC).
1 pound (450g) strawberries, hulled and quartered or sliced
4 cups (800g) plus 1/4 cup (60ml) sugar
2 pounds (900g) purple plums, pitted and cut into sixths
optional: 1/2 to 1 teaspoon kirsch, or a squeeze of lemon juice, if desired
1. Toss the quartered or sliced berries in a Dutch oven or similar sized pot with 1/4 cup (50g) of the sugar.
Let marinate for a few hours, stirring every once in a while, or overnight.
2. Add the plums to the pot and cook over medium heat, covered, until the plums are cooked through.
Use an immersion blender to puree the berries and plums, leaving them chunky, if you wish.
3. Add the rest of the sugar (4 cups/800g) to the pot, and attach a candy thermometer to the side, if you wish.
Put a small plate in the freezer.
Cook the jam over medium-high heat, stirring in the sugar, until it dissolves.
Continue to cook, skimming any scum that rises to the surface during the first part of the cooking.
Stir it frequently with a silicone spatula or flat-bottom utensil (so you can scrape the bottom as you stir) until the jam has thickened and the jam sticks in a clump to the bottom of the spatula or utensil. (As shown in the post.)
3. When you think the jam is done (even if using a candy thermometer), test it by turning the heat off and putting a teaspoon-sized dab of the jam on the chilled plate and return it to the freezer for a few minutes.
When you nudge it with your finger, if it wrinkles or appears jelled, it’s done.
If not, continue cooking it a few more minutes, stirring frequently, then test it again.
When ready, add a bit of kirsch or lemon juice, if using, then ladle the jam into clean jars.
The jam should keep in the refrigerator for at least six months.
If you wish to preserve it longer, or at room temperature, I’ve linked to a food preservation website in the headnote before the recipe with canning instructions.
You can leave the fruits relatively chunky, or puree them until smooth.