Place oil in a large skillet; heat over medium. Add onion; cook, stirring often, 5 minutes. Add sugar snap peas; cook, stirring often, until bright green and crisp-tender, 5 to 6 minutes. Add honey and salt; cook, stirring constantly, 1 minute. Remove from heat.
Stir together broth and 3/4 cup of the half-and-half in a medium bowl. Transfer half of the sugar snap pea mixture and half of the broth mixture to a blender. Process on high until very smooth, 30 to 60 seconds. Pour through a fine wire-mesh strainer into a large bowl. Repeat procedure with remaining sugar snap pea mixture and broth mixture. Stir lemon juice into blended mixture in bowl. Cover and chill until cold, at least 4 hours and up to 12 hours.
Stir together sour cream and remaining 2 teaspoons half-and-half in a small bowl. Ladle 1 1/4 cups chilled soup into each of 4 serving bowls. Dollop or swirl each bowl with about 1/2 tablespoon sour cream mixture. Garnish with fresh chives and chive flowers.