Combine flour, sugar, and salt in a large mixing bowl. Cut butter into flour mixture until it is finely mixed.
Combine egg yolk, water, and lemon juice with a fork. Sprinkle egg yolk mixture over flour mixture and stir together with a fork until it forms a ball.
Pull small pieces of pastry from the ball and press into bottom and sides of the tart pans to about 1/8 inch thickness. Refrigerate until ready to use.
To make the filling, chop rhubarb into 1 inch pieces. Cook on low until soft. Mash if needed.
Add raspberries and lemon juice and then honey to taste.
Spoon filling evenly into tart shells, filling each no more than 2/3 full.
Bake at 425° F for 10-15 minutes or until golden brown. Remove from oven and cool, in pans, for 15 minutes. Remove from pans to cooling racks and cool completely.