For the Salad: In a large bowl, combine rice, tuna, olives, scallions, bell pepper, and green beans. Using two big forks, toss gently until well combined and rice grains are separated.
Drizzle with the dressing and toss gently, fluffing the rice, until evenly dressed. Garnish with cilantro leaves, if using. Serve at room temperature.
Make-Ahead and Storage
Leftovers can be refrigerated for up to 1 day, but should be brought back to room temperature before serving.
In a 3- to 4-quart stainless-steel saucepan or enameled Dutch oven, combine yogurt, 2 cups (475ml) water, and cornstarch and bring to a boil over medium-high heat, whisking constantly to prevent curdling (you do not want the yogurt to break into curds, so constant whisking until it boils is absolutely essential). Reduce heat to a bare simmer, whisking occasionally to prevent scorching. Season with salt.
Notes
To reheat any leftovers, add water and reheat slowly on the stove, adjusting seasoning if needed.
Labaniyeh bil ruz can be refrigerated in an airtight container for up to 5 days. Reheat slowly on the stovetop, thinning with water and adjusting seasoning as needed.
