Step 1Bring 1 cup of water to a boil in a small saucepan, add the raisins and turn off the heat. Let sit for 5 minutes, then drain and transfer the raisins to a small bowl. Mix in the rose petals; set aside to cool.
Step 2In a medium saute pan over medium-high heat, toast the walnuts until fragrant, 1 to 2 minutes. Remove from the heat; cool.
Step 3In a large bowl, combine the yogurt, shallot, herbs, salt and pepper and mix with a rubber spatula until well blended. Add the sliced cucumbers and radishes, and stir to combine.
Step 4Just before serving, add the walnuts and raisin mixture and stir well to combine. Transfer to a serving bowl and garnish the outer edge of the bowl with sprigs of basil, mint and dill. Scatter a few rose petals over the top.