In a 4-quart Dutch oven cook onion and garlic in hot oil over medium heat about 5 minutes or until onion is tender, stirring occasionally. Remove onion and garlic from the Dutch oven; set aside.
Add broth to the same Dutch oven. Bring to boiling. Add the broccoli and edamame. Return to boiling; reduce heat. Simmer, uncovered, for 3 to 5 minutes or just until broccoli is tender. Using a slotted spoon, transfer broccoli and edamame to a large bowl; set aside.
Add spinach to the hot broth mixture in Dutch oven. Cook and stir about 1 minute or until spinach begins to wilt. Remove from the heat. Cool slightly. Stir broccoli mixture and onion mixture into spinach. Add spinach mixture and tofu, half at a time, to a blender or food processor. Cover and blend or process until very smooth.
Return all of the blended mixture to the Dutch oven. Add yogurt, salt and pepper. Cook over medium-low heat just until heated through, stirring occasionally. Ladle into bowls. Top with soy nuts and chives.