Romaine with sauteed pears

Ingredients

• 1 tbsp red-wine vinegar
• 1 1/2 tsp honey
• 1 1/2 tsp Dijon mustard
• 1/8 tsp salt
• 1 tbsp olive oil
• 2 Bosc pears
• 1 tbsp butter
• 1 head romaine lettuce , thickly sliced
• 1/2 cup chopped toasted pecans , optional
• 1-in. chunk parmesan , about 28 g