To prepare the soup: In a large saucepan melt butter and add diced pears, chopped onions, sliced leeks minced garlic and sauté for 2 minutes. Add flour and curry powder and sauté until the pears become soft, about 5 minutes.
Next stir in chicken stock and dry white wine. Reduce the heat and simmer until the soup is slightly thickened, about 15 minutes.
Use an immersion blender to puree the soup - it will take about 2 to 3 minutes. You can use a blender by adding small batches at a time or a food processor.
For the yogurt garnish: Melt butter in a skillet over medium heat add sliced scallions and sauté until tender, about 2 minutes. Add honey and sesame oil and cook for about a minute.
Remove from the heat and stir in plain yogurt. Taste and adjust seasoning as desired with salt and pepper. Ladle the soup into bowls and top with the garnish.