Make the dressing. In a large bowl, whisk the mustard and lemon juice. In a slow stream, drizzle the olive oil into bowl while still whisking. Taste and season the dressing with a pinch of salt and few grinds of black pepper. Add red onion, parsley and thyme.
Grill the mushrooms. Heat grill to medium heat. Push mushrooms on the grill combs through the side. Drizzle mushrooms with olive oil on all sides, then sprinkle with onion powder, salt and pepper. Place on the grill and cook until charred on both sides, flipping only once, about 8 minutes total. Remove and allow to cool enough to handle.
Toast the pine nuts. In a dry pan on medium heat, add the pine nuts and continuously toss until they become shiny and slightly golden, about 4 minutes. Remove from heat.
Make the salad. Lightly chop the grilled mushrooms and toss in the bowl with the dressing. Remove to a serving plate or bowl with a slotted spoon. Top with shaved cheese and pine nuts. Serve warm or room temperature.
The Old-School Tough.