In large saucepan brown ham in hot oil over medium heat without stirring for 3 minutes. Stir and brown the other side for 2 to 3 minutes.
Add peas, water, broth, carrots, celery, green onions, and tarragon. Bring to boiling. Reduce heat; simmer, covered, for 5 to 10 minutes or until peas and carrots are tender.
To serve, divide soup among four soup bowls. Pass lemon wedges and yogurt. Makes 4 servings.