Place the strawberries in a ceramic bowl, then toss with the lemon juice and sugar. Cover with a sheet of parchment and let macerate overnight in the refrigerator.

The next day, pour the strawberry mixture into a non-reactive stockpot (copper is ideal for jam-making). Bring to a simmer over medium-high heat. Pour it back into the ceramic bowl, cover with parchment again, and refrigerate overnight.

The third day, set a mesh sieve over the stockpot. Pour the strawberry mixture into the sieve and bring the liquid that comes through the sieve to a boil over high heat. (Reserve the contents of the sieve and set aside.) Skim any foam from the top of the syrup, and continue cooking over high heat until the temperature reaches 220˚F. Add the strawberries from the sieve, and stir in the mint and black pepper. Return to a boil, skim again, lower the heat to medium, and simmer, stirring, for 5 minutes.

Use a small ladle and a funnel to pour the jars into sterilized jars (see note). Fill right up to the top. Seal with sterilized lids while the jam is hot, then turn the jars upside down and wipe them with a clean, damp towel. Allow to cool before labeling, and store in a cool, dark place.