In a medium bowl, gently toss together blackberries, blueberries, oranges, orange juice, lemon juice, and salt. Cover and refrigerate for 1 hour.
Heat a cast-iron grill pan over medium heat; brush with melted butter. Add pound cake; cook until grill marks form, about 1 minute per side. Cut cake into cubes.
Add basil and mint to berry mixture, gently stirring until combined. Spoon onto serving plates. Top with grilled pound cake. Drizzle with Citrus-Yogurt Sauce. Garnish with basil and mint, if desired. Serve immediately.
Citrus-Yogurt Sauce
In a small bowl, whisk together all ingredients. Serve immediately, or cover and refrigerate for up to 2 days.
Recipe by Louisiana Cookin' at https://louisianacookin.com/berry-orange-panzanella/