If you’re told you cannot do something, does that make you give up or does it challenge you to succeed?

When Gordon Au attended the University of Hawaii, he asked a professor if he could earn his degree in food sciences. The professor told him that with his grades, that goal wouldn’t be achievable.

Fast forward 10 years — Au has his degree and is a dietary aide at Adventist Health Castle. The vegetarian pho that he cooks once a week is one of the best-selling dishes in the medical center’s cafeteria.

This Roosevelt High School graduate is no stranger to the culinary world. His parents, Albert and Stella Au, are part owners of Golden Wheel Chinese Restaurant in Aiea.

On the day (usually a Wednesday) that he makes his delicious pho, he serves up to 80 employees and visitors. Although he started with a basic recipe, he has perfected it over the years and made it his signature.

Au demonstrated his dish recently as part of Castle’s Eat Well for Life monthly cooking series.

It is a satisfying dish that includes many textures from fried seasoned tofu, crispy vegetables and sauces you select to your liking.

The classic Vietnamese pho broth usually gets its strong flavor from meat and spices.

Au uses a variety of spices —black peppercorns, cinnamon sticks, onion, star anise and cloves. To bring out the flavor, he roasts the spices, then adds water and brings it all to a boil. His secret soup ingredient — Minor’s Mushroom Base — is difficult to find in Hawaii, but he says he prefers this brand over others. Find it at ChefZone or online.

Instead of pieces of brisket, raw beef, tendon or tripe, Au substitutes deep-fried cubes of firm tofu, which provide a contrast in textures. The outside is golden and crisp while the inside of the tofu remains tender.

After frying the cubes, he marinates them in soy sauce and a refreshing dried vegetable and herb mixture called Durkee Garden Seasoning. You could substitute any spice mix, as that item seems to be available only online. Reduce the soy sauce if your spice mixture includes salt.

The condiment tray that Au offers with his dish of soup, noodles and fried tofu makes this dish even more spectacular. He serves a platter of chopped green onions, cilantro, Thai basil, jalapenos, lime wedges, Sriracha hot sauce and hoisin sauce.

You could also prepare bean sprouts, mint leaves and other Southeast Asian herbs such as culantro or rau ram (both also called Vietnamese cilantro).

Castle Wellness Center director and pho devotee Tracie Ann Tjapkes says a taste of the pho makes it obvious that Au takes pride in his cooking.

He is meticulous in preparing his ingredients and has favorite brands. In addition to his favorite mushroom base and herb seasoning, Au prefers Aloha Shoyu, House Foods tofu and specific brands of rice noodles (Super Chef or King).

He is proud that the employees and outside visitors enjoy his vegetarian invention and is doubly happy that he was able to prove that professor wrong.

VEGETARIAN PHO

By Gordon Au

• 1 (16-ounce) package dry rice sticks (Super Chef or King Brand preferred)

>> Broth:

• 1/2 medium onion, peeled and cut in wedges
• 4-inch piece ginger, peeled and sliced
• 5 star anise pods
• 1/4 cup whole black peppercorns
• 10 cloves
• 1 (2- to 3-inch) stick cinnamon
• 2 gallons water
• 1/4-1/2 cup mushroom base (Minor’s brand preferred)

>> Fried tofu:

• 2 (14-ounce) blocks firm or extra-firm tofu (House Foods brand preferred)
• About 3 cups canola oil (enough to cover tofu), may substitute vegetable or olive oil
• 1/4 cup soy sauce (Aloha brand preferred)
• 1-3 tablespoons Durkee Garden Seasoning, substitute no-salt dried herb seasoning (if using herb seasoning with salt, reduce amount of soy sauce)

>> Toppings and sauces: Chopped cilantro and green onions, Thai basil leaves, lime wedges, sliced serrano or jalapeno chilies, bean sprouts, hoisin and Sriracha sauces

>> To make broth: In a large pot over medium-high heat, sear onion, ginger, star anise, peppercorns, cloves and cinnamon stick 5 to 10 minutes, until fragrant. No oil is needed. Alternatively, roast spices in a 350-degree oven for 5 to 10 minutes.

Add water; bring to a boil. Add 1/4 cup mushroom base (or substitute 1 to 2 cups mushroom seasoning). Taste broth and add up to 1/4 cup additional mushroom base if needed. Boil 15 minutes, then simmer 10 to 15 minutes.

Strain out seasonings. Broth may be prepared a day in advance and refrigerated. Makes 2 gallons, enough for 16 2-cup servings. Leftovers may be frozen.

>> To make fried tofu: Cut tofu into bite-sized cubes (no need to drain).

In a pot, heat enough oilto cover the tofu. All of the cubed tofu can be cooked at once in a 6-inch stock pot, requiring about 3 cups of oil. To use less oil, fry the tofu in batches. Deep-fry tofu cubes until deep golden brown, but still tender inside, 15 to 20 minutes. Alternatively, bake in a 350-degree oven for 30 to 45 minutes.

Drain fried tofu and place in bowl. Add soy sauce and toss. Add herb seasoning and toss. Taste. Add more soy sauce or seasoning, if needed. Set aside.

>> To make noodles: Bring pot of water to boil. Add noodles and cook until tender, no more than 5 minutes. Rinse and cool.

>> To serve: Arrange toppings in a tray. Place noodles in serving bowls. Pour hot broth over noodles and top with fried tofu. Let guests select toppings to taste. Serves 8.

>> Tips: Be sure to strain the broth so the hard spices do not spoil the enjoyment of the pho. Cook rice noodles hours ahead of serving. Refrigerate, then rinse in hot water just before serving, to warm, separate and soften them. Take time to clean your garnishes well and cut them attractively.

Approximate nutritional information, per serving: (not including adding any additional ingredients to taste): 450 calories, 14 g total fat, 1.5 g saturated fat, no cholesterol, greater than 1,500 mg sodium, 55 g carbohydrate, no fiber, 3 g sugar, 24 g protein.

Lynette Lo Tom, author of “The Chinese Kitchen,” is fascinated by old-fashioned foods. Contact her at 275-3004 or via instagram at brightlightcookery. Nutritional analysis by Joannie Dobbs, Ph.D., C.N.S.