Sterilize the jars by boiling, or in the dish washer. Put the strawberries in the pot with anywhere from 1 to 3 tablespoons of water (so they don't burn before they begin to release their juice) and set over medium heat. As soon as you get some juice running (which will be very soon), add the sugar to the berries. Stir to dissolve sugar (Flo uses a metal spatula,) scraping across the bottom to prevent sugar or strawberries from burning. "Very very shortly, you're going to have oodles of liquid," Flo explained.
Once the sugar is dissolved, Flo turns the heat up to high to get the pot boiling. She stands and stirs until the entire pot is involved in an active boil, then she reduces the heat to medium once again. "At that point you can walk away," she said. She returns and stirs every 5 to 15 minutes (Flo keeps a timer in her pocket) making sure nothing is sticking on the bottom.
The strawberry jam will boil slowly for nearly 2 hours. The strawberries will start shrinking as they release their juice. The pot will develop a pink foam on top. All of this is expected. The thing to watch for is sticking on the bottom. If the jam starts sticking, reduce the heat.
It starts to get close, Flo says, when the jam starts spitting and popping, and that as she stirs, the mixture feels heavy. Flo puts some ice in a pie pan, spoons some jam onto a plate, sits the jam on top of the ice to cool, and checks it for consistency. If it's still liquid and runny, it's not ready. Finished jam looks literally like curds of ruby red jelly with chunks of strawberries scattered throughout.
Flo skims off the pink foam, reduces the heat, and fills the jars while the jelly is still at a low boil. That way she is sure everything stays sterile. The jar lids are sitting in very hot water until they are wiped dry and spun onto the jars of jam. "Don't cool them under a fan, and don't let the jars touch until they are cool, otherwise they might crack," Flo said. More wisdom, passed down from her mother. I'd follow all her advice.
Yield: 6 half-pints