Preheat oven to 375 degrees F.
Toss together the rhubarb, strawberries, granulated sugar, flour, lemon zest, lemon juice and salt in a large bowl and let sit, tossing gently one or twice, for 10 minutes. Spoon into a 9 by 13-inch or similar volume baking dish.
For the topping, stir together the flour, pecans, granola, oats, brown sugar, dried cranberries, granulated sugar, cinnamon, allspice and salt in a medium bowl until well blended. Add the butter pieces and stir well to evenly distribute the butter with the dry ingredients.
Scatter the topping evenly over the fruit. Set the baking dish on a baking sheet to catch any drips and bake for 30 to 35 minutes, until the edges are bubbly and the topping is lightly browned. Let sit for at least 10 minute before serving; serve warm or at room temperature.