For the vinaigrette:
Combine lemon juice, zest, mayonnaise, honey, salt, pepper, basil and olive oil in a blender and blend until smooth. Can be made 1 hour in advance and refrigerated.
For the mushrooms:
Heat the grill to high.
Place the mushrooms in a large bowl, add the canola oil and salt and pepper and toss to coat. Skewer mushrooms, 4 on a skewer. Place the mushrooms on the grill, until golden brown and slightly charred, 4 to 5 minutes. Turn over and continue grilling until just cooked through, 3 to 4 minutes longer. Remove from the grill to a cutting board and quarter.
Place the celery and parsley in a large bowl, add half of the vinaigrette and toss to combine, season with salt and pepper. Top with the mushrooms and drizzle with more of the vinaigrette. Squeeze lemon juice over the salad and serve.