Asparagus-Tomato Stir-Fry
["1 Tbsp. water (cold)", "2 tsp. soy sauce", "1 tsp. cornstarch", "1/4 tsp. salt", "1 lb. fresh asparagus", "1 Tbsp. vegetable oil", "4 green onions, sliced", "1 1/2 sliced fresh mushrooms", "2 small tomatoes, cut in wedges"]
["Combine first 4 ingredients in a small bowl, stirring until blended.", "Set aside."]
["water", "soy sauce", "cornstarch", "salt", "fresh asparagus", "vegetable oil", "green onions", "mushrooms", "tomatoes"]