Candy the pecans: In a skillet, melt 2 tbsp sugar with 1 tsp butter over medium heat. Stir in pecans until coated, then transfer to parchment paper to cool.
Whisk together dressing ingredients until smooth.
In a large bowl, arrange arugula, pears, gorgonzola, red onion, and candied pecans.
Drizzle with dressing just before serving.