For the quick pickle: In a small saucepan over medium heat, combine the vinegar, water, sugar and salt and bring to a simmer. Remove from the heat and allow to cool for 5 minutes.
In a small bowl, pour the brine over the cucumbers and allow to sit at room temperature for 30 minutes.
For the salad: In a large bowl, whisk together the oil, vinegar, mustard and salt. Add the grapes, blueberries, radicchio and endive and toss well to coat. Drain the cucumbers and add them to the bowl along with the gorgonzola picante and pistachios. Toss one last time and serve.