In a small bowl, whisk together the vinegar, mustard and garlic, slowly add the olive oil and whisk until combined. Season with salt and pepper. Pour 1/2 the marinade over the vegetables and let sit at room temperature for 15 minutes. Heat a large deep saute pan, once hot add zucchini and sugar snap peas.  Saute for 5-10 minutes until desired doneness.  Remove from pan and set aside.

Add the olive oil to the pan and bring over medium-high heat, add the couscous and toast until lightly golden brown. Pour in the water or stock and bring to a boil then cover and simmer for about 10 minutes, until couscous is al dente and water is absorbed.

Place in a large serving bowl, add the grilled vegetables, tomatoes and herbs and toss with the remaining vinaigrette. Serve at room temperature.