Marinated Flank Steak with Tomato Cous cous

I made this for Shabbat dinner with my mom was in town for the weekend. I marinated the steak, but I can't remember exactly what i marinated it in. It was in the fridge for a while and then marinating at room temperature until Blake grilled it. We served it with the warm cous cous and a green salad with challah, all after the potato soup. I found the cous cous recipe on foodgawker a while back and had been waiting for a chance to make it.

Steak Marinade:
Balsamic Vinegar
Honey
Garlic
Dried Herbs
Salt, Pepper

Cous Cous Ingredients:
1 cup Israeli couscous
Kosher salt
2 tablespoons extra virgin olive oil
1 large yellow onions, halved and sliced
1 tablespoon brown sugar
1 tablespoon balsamic vinegar
3/4 teaspoon turmeric
1 pint cherry tomatoes, halved

Directions:
Heat the olive oil in a large, wide skillet over medium-high heat, then add the onions and 1/2 teaspoon salt. Saute, tossing occasionally with tongs, for about 15 minutes. Sprinkle in the brown sugar, balsamic, turmeric, and 1/4 teaspoon more salt, and continue cooking, and giving a stir or two, over this assertive heat for 5 more minutes. Then reduce the heat to low and cook, tossing frequently, for 10 minutes longer, or until very soft, glisteny, and sweet. Meanwhile, boil water and drop the couscous in to cook until al dente, about 7 minutes. Drain and rinse briefly under cool water. Stir in the cooked couscous, top with the tomatoes, and serve warm, or at room temperature.