In a medium saucepan, combine the rhubarb, strawberries, lemon zest, juice, and sugar. Bring to a boil over medium heat, stirring every now and then. Once the sugar has dissolved and the mixture is at a boil, turn it down to a simmer and cook until rhubarb is soft and falling apart, another 5 minutes. Remove from the heat. Add the rosewater and stir. You can serve the compote warm or cold.
In a small, nonstick skillet, melt the butter over medium heat. Add the sugar, cardamom, almonds, and a pinch of salt. Cook, tossing occasionally, until the almonds are toasted and the sugar caramelizes and sticks to the almonds.
To build a parfait, spoon 1 cup yogurt into 4 bowls, spoon about 1/2 cup of compote over the top, and sprinkle candied almonds to finish.
Cook's Note: If you're using fresh rhubarb, peel the fibrous strings off the outside of the rhubarb using a paring knife (dip the knife under the top layer of the rhubarb stalk and peel down to the end of the stalk).