Garden Vegetable Stir-fry with Tofu and Brown Rice

The other day I went to Costco and bought a HUGE bag of frozen stir-fry veggies (broccoli, onion, baby corn, water chestnuts, bell peppers) for like $9 and decided it's about time I find a good stir-fry recipe to use these fabulous veggies. I have to admit I am not very familiar with cooking with traditional Asian staples (rice wine vinegar, sesame oil), and this one looked simple enough to try.

I found this recipe from Cooking Light. The results were pretty good, not great - but good enough to attempt to modify and work with again. I know that my tofu could have been a little crispier and in bigger chunks; maybe I'll even use chicken next time.

Ingredients
2 tablespoons water
1 1/2 tablespoons cornstarch
1 cup canned vegetable broth - I thought I was opening a can of chicken broth and discovered it was a can of beef broth so went ahead and used it; I think this would have been better with vegetable or chicken
2 tablespoons oyster sauce
2 tablespoons low-sodium soy sauce - I used Bragg's Aminos but should probably have used Soy Sauce
1 tablespoon rice vinegar
1 teaspoon sugar
1 teaspoon dark sesame oil
1/2 teaspoon crushed red pepper
3 teaspoons vegetable oil, divided
1 (12.3-ounce) package reduced-fat firm tofu, drained and cut into 1/2-inch cubes - when I went to the store they only had it pre-cut in smaller cubes; I would have liked it in bigger cubes or even strips. Maybe in the future I'll use chicken??
1 cup cilantro sprigs - I omitted these.. I thought I had cilantro in my garden but I apparantly had killed it... I am no green thumb :(
3 cups hot cooked long-grain brown rice - suggestion: use Basmatic or sticky rice. As much as I love whole grains I just can't embrace cheap brown rice
About 4-5 cups, or 1/4 of the Costco Frozen Stir Fry Veggie bag. I used this in place of the following from the Cooking Light Recipe:
--1 cup thinly sliced onion
--1 cup red bell pepper strips
--3 cups sliced zucchini (about 3/4 pound)
--1 cup snow peas, trimmed
--1/2 cup diagonally sliced carrot
--1 (8-ounce) can sliced water chestnuts, drained

Preparation
Combine water and cornstarch in a bowl; stir with a whisk. Stir in broth and next 6 ingredients (broth through crushed red pepper).
Heat 2 teaspoons of vegetable oil in a large nonstick skillet over medium-high heat. Add tofu; stir-fry 8 minutes or until golden brown, stirring occasionally. Remove tofu from pan. Place tofu on several layers of paper towels.
Add 1 teaspoon vegetable oil to pan. Stir-fry the frozen veggies until heated through, about 8 minutes. (If you are NOT using frozen veggies, do this: Add onion and bell pepper, and stir-fry 2 minutes. Add the zucchini, snow peas, carrot, and water chestnuts; stir-fry 1 minute.)

Add tofu and broth mixture. Bring to a boil, and cook 2 minutes (mine took longer- about 5 minutes - to thicken). Stir in cilantro. Serve with rice.


Finally: this had a slightly tangy aftertaste that I did not particularly enjoy (the husband didn't seem to mind it, I think it's just my own personal preference); I am not sure if it's from the sesame oil or maybe even from one of the veggies (I have a love/hate relationship with bell peppers). I don't think it's the Oyster sauce because I've used that several times before. If you are familiar with Asian flavors, please comment to enlighten me on what that tangy aftertaste was and what I can do to prevent it.