For the soup: Preheat a grill for direct and indirect cooking or oven to 400 degrees F. If using a grill, set a wire rack directly on the grill grate.
Brush the asparagus and scallions all over with olive oil. Sprinkle with salt and pepper and place over the direct heat of the grill. Cook, turning a few times, until limber and partially charred, 2 to 4 minutes. Remove to a cutting board.
Make the toast: In a small bowl mix the jam and sambal. Spread on the cut side of the rolls. Divide and pile the cheese on top of the jam on each roll and place over the indirect heat of the grill (directly on the grates or on a baking sheet). Cook, covered, until the cheese is melted, 3 to 5 minutes.
Build the soup. Transfer the grilled veggies to a cutting board and roughly chop. Add to the jar of a blender. Add the stock, yogurt and parsley and blend until smooth.
Put the soup, lemon zest, garlic and salt to taste in a medium pot over medium-high heat and bring to a simmer. Cook for a few minutes to warm through. Taste and adjust the seasonings if needed.
To finish the soup: In a small bowl, whisk together the yogurt, lemon juice and honey. Pour the soup into bowls. Spoon 3 drops of the yogurt mixture into each bowl and run a skewer in a circle through the yogurt mixture to make a decorative pattern.
Serve the toast alongside the soup.
The asparagus and scallions can be grilled or roasted.