HEAT oven to 350ºF.
BRING water and quinoa to boil in saucepan on high heat; simmer on medium-low heat 15 min. or until water is absorbed. Transfer to medium bowl; cool.
ADD beans and 1 Tbsp. taco seasoning; mix well. Spread onto bottom of 13x9-inch baking dish; cover with zucchini and peppers. Sprinkle with remaining taco seasoning; top with salsa.
BAKE 35 min. or until heated through. Top with cheese; bake 5 min. or until melted.