Combine the strawberries and sugar in a heavy saucepan. Stir in the grated apple and lemon juice.
Cook over medium-high heat, stirring to break up strawberries, and simmer until jam is thickened, about 10-15 minutes.
Transfer to a bowl or jar and let cool. Cover and chill until set, about 2 hours.
Keep chilled and serve within 2 weeks. Also freezes well.
This jam is not too sweet and has a bright, fresh flavor. Adding a grated apple (a pectin-packed fruit) naturally thickens the jam.
Any berry can be used for this jam.
1poundfresh hulled and quartered strawberries
1large apple, peeled and coarsely grated
1tablespoonfresh lemon juice