Orange Tofu with Mushrooms

I had heard so much about how good the orange chicken is and always wanted to make the "veggie" version of it. Then I came across this recipe from PhamFatale and so wanted to try it out. I made some changes to the original recipe, substituting some of the ingredients with my own.
Ingredients:
1 (12-ounce) package firm tofu
1 small white onion
1 teaspoon fresh ginger, finely minced
2 cups orange juice, freshly squeezed
3/4 cup soy sauce
1 tablespoon brown sugar, depending on how sweet the oranges are
1 clove garlic, finely minced
1-1/2 tablespoons ketchup
1 teaspoon tomato paste
1 teaspoon chili garlic sauce
1/2 teaspoon sea salt
7 tablespoons tapioca starch
3 tablespoons rice vinegar
2/3 cup water
5 tablespoons canola oil
1 tablespoon lime juice
1/4 teaspoon black pepper, freshly ground
12 button mushrooms,  sliced
1 tablespoon cilantro, finely chopped
1 tablespoon green onion

Method:
For the orange sauce mix the tapioca starch, soy sauce,2 teaspoons brown sugar, ketchup, tomato paste, chili garlic sauce and 2/3 cup water . Set aside.

In a pan,pour 1 teaspoon of oil. Add the minced fresh ginger and cook for about 1-2 minutes. Add 1 1/2cups of orange juice. Bring to a boil. Add the tapioca mixture  that is set aside and stir constantly to prevent the starch from sticking to the bottom of the wok. Continuously stir the broth as it will thicken very quickly.

In  wok, heat about 2 teaspoons of oil. Add the garlic and onion saute till the garlic turns slightly golden.Add the sliced mushrooms. When the color is translucent and shiny, season with salt. Add about 1/2 cup of orange juice and a teaspoon of brown sugar. Cook for about 3-4 minutes. The mushrooms should be tender, yet still firm. Transfer the mushrooms to the orange sauce which should be thick and syrupy. If you find the sauce to be too thick, add 2 to 4 tablespoons of water.
Drain and pat dry the tofu.Slice the tofu into 1" thick pieces.Fry the tofu in medium heat on all sides and immediately dip the tofu into the orange-flavored sauce. The tofu will deflate instantly. Finish with lime juice, cilantro,green onion and black pepper. Toss well.