Steam green beans for approximately 3-5 minutes, until tender.
Meanwhile bring sugar and water to a boil in a small saucepan over med-high heat, stirring constantly to dissolve sugar. Remove from heat. Stir in cranberries, and let stand 10 minutes.
Whisk together fish sauce, sriracha, and sesame oil in a large bowl. Stir in cranberry mixture.
Add green beans to bowl and toss to coat.