Cut the rhubarb into half-inch pieces.
In a medium, nonreactive saucepan, bring the rhubarb, 2/3 cup water and the sugar to a boil. Reduce the heat, cover and simmer until the rhubarb is tender and cooked through, about 5 minutes.
Cool to room temperature.
Slice the strawberries and puree them in a blender or food processor with the cooked rhubarb mixture and lemon juice until smooth.
Chill the mixture thoroughly, then freeze in an ice-cream maker according to the manufacturer's instructions.
In a medium, nonreactive saucepan, bring the rhubarb, 2/3 cup water and the sugar to a boil. Reduce the heat, cover and simmer until the rhubarb is tender and cooked through, about 5 minutes.
Cool to room temperature.
Slice the strawberries and puree them in a blender or food processor with the cooked rhubarb mixture and lemon juice until smooth.
Chill the mixture thoroughly, then freeze in an ice-cream maker according to the manufacturer's instructions.