To make the vinaigrette, whisk together the vinegar, mustard, honey, sesame seeds, garlic, and salt and pepper, to taste, in a bowl. Gradually whisk in the oil. Set aside.
To make the curried cashews, preheat the oven to 400 degrees F.
On a baking sheet, toast the cashews until golden, 8 to 10 minutes. Meanwhile, combine the melted butter, rosemary, curry powder, brown sugar, salt, and cayenne in a bowl. Add the toasted cashews while they are still hot and toss with a rubber spatula so they are thoroughly coated with the spices and butter. Leave the oven on to cook the bacon.
Put the bacon on a baking sheet, place it in the oven, and cook until crisp, 8 to 10 minutes. Remove the bacon from the pan and cut the slices into 1-inch pieces. Keep the bacon warm.
In a large bowl, combine the spinach, frisee, red onions, and sliced pears. Toss with enough vinaigrette to coat everything well.
Divide the salad among 6 plates. Garnish each salad with pieces of warm bacon and spiced cashews. Set a grape cluster on the side of each salad.
The bacon can be cooked ahead, stored in the refrigerator, and reheated. The cashews can be cooked early in the day and stored at room temperature. The vinaigrette can be stored refrigerated, tightly covered, for several days.