Place a tablespoon of olive oil each into a frying pan and small pot. Heat until sizzling.
Add couscous to the pot and allow pasta to brown for a couple of minutes. Shake pot every 30 seconds or so to distribute heat. Add four cups water, cover, and bring to a boil.
Add minced garlic to the frying pan, and sauté for two minutes or until golden and fragrant. Add beef fry, if using, and sauté for a few minutes.
Clean mushrooms, and slice larger ones in half. Pat dry with paper towel. Add to frying pan, and allow to cook for four to five minutes or until mushrooms are shiny and slightly browned.
Meanwhile, clean and slice scallions, separating white and green parts. Add white parts of scallion to the mushrooms, and season with salt and pepper. Stir until scallions are softened and remove from heat.
When water is evaporated, turn off couscous pot and remove from heat. Break up clumps using a fork or gloved hand. Add dark parts of scallions, a drizzle of olive oil, salt, and pepper. Mix.
Serve couscous warm with mushrooms in the center. Sprinkle with sesame seeds immediately before serving.