Combine rhubarb, and strawberries in bowl. Sprinkle on sugar, tapioca, salt, and spices. Mix gently. Turn into pastry lined 10 inch pie pan, dot with butter. Add pastry top, flute edges.
Bake in 400 degree oven, on bottom rack, for 40 minutes, or until crust is browned and juices bubble. Cool on rack. This can also be made in a 9 inc square pan.