Combine strawberries and sugar in a flat-bottomed kettle; mix well, and let stand 3 to 4 hours.
Slowly bring strawberry mixture to a boil, stirring until sugar dissolves. Add lemon juice. Boil, stirring occasionally, 12 minutes or until berries become translucent. Remove from heat; skim off foam with a metal spoon.
Remove strawberries from syrup with a slotted spoon, and place in a shallow pan. Bring syrup to a boil; boil, stirring frequently, 10 minutes or until desired consistency. Pour syrup over strawberries. Let stand, uncovered, 12 to 24 hours in a cool place. Shake pan occasionally so berries will absorb the syrup and remain plump and whole. (Do not stir.) Skim off foam with a metal spoon.
Ladle preserves into hot sterilized jars, leaving 1/4-inch headspace. Cover at once with metal lids, and screw bands tight. Process preserves in boiling-water bath 15 minutes.