Ammi was quite remarkable and I cannot give her enough credit for what became of me. (1.17)
Hassan credits his success to his grandmother, whom he remembers being sharp and vivacious when he is a very small child. This shows that he's always been a person who learns from looking up to other people.
But you had to admire Papa, the charisma and determination behind his immense drive. (1.37)
Hassan gets his business streak from Papa, who singlehandedly runs the family restaurant in Mumbai, as well as supports the whole family. Although Hassan doesn't have quite the same charisma and personality as Papa, his dad gives him a great example to live by.
Mummy sat on the blanket, curled into herself like a pink pomegranate. She turned gaily, her teeth white, her hands stretched out to help my sister. That is how I like to remember Mummy. (2.82)
This is a pattern that Hassan has throughout the story. He likes to remember everyone at their absolute best, and so he takes a pretty picture to think of them by. This natural goodwill makes it easy for Hassan to admire people.
"No? Hmm. Not very impressive. Perhaps she is not as good as we think."
"No, Papa. She is a great chef." (12.36)
In his first few months at Le Saule Pleureur, Hassan works super hard doing lots of boring work. The thing that gets him by and makes him keep working is that he looks up to Madame Mallory as an example of what he wants to become. His respect for her inspires him to work without giving up.
I was very happy working alongside white-haired Marc Rossier, an elderly chef who had his own ways. […] This rewarding work at La Belle Cluny whet my appetite, and at the age of thirty I returned to Lumière to have an earnest talk with Papa. (13.9-13.11)
Hassan's admiration for his boss and enthusiasm to learn from him is what inspires him to want to open a restaurant of his own. As far as Hassan's concerned, every person is someone to learn from in order to make himself better.
But over the following years, Verdun and I definitely established a deep and abiding professional respect for each other, even, I would say, one of real affection. (13.83)
Hassan and Verdun's friendship is admiration to the max in both directions. What starts as a business connection turns into an inspirational friendship that benefits both men. Hassan doesn't even think to see Paul as a threat or competition, but is instead just excited to meet someone more experienced than himself.
Economists have had their own explanation as to what happened during this dark period, but I like to think the universe at large was itself reacting to the news that Abbas Haji and Gertrude Mallory were no more a part of this life, but had finally been summoned to the abattoir. (13.116)
Hassan's two greatest heroes die, and he's left incredibly depressed and discouraged. Poetically, he states that everything around him—even the crash of the economy—is due to the absence of these two awesome people in his life.
"Paul really had affection only for you, Hassan. He once told me that you and he were 'made from the same ingredients.'" (15.45)
Paul's widow tells Hassan that her late husband had great admiration for him. He considered his friend like-minded and in possession of the same understanding of their shared art form. Paul and Hassan were never competition for each other because they had a healthy way of looking up to each other and both enjoying the same things.
And I tell you, as I looked out at all those good people—red-faced and stuffed with my food—I suddenly felt my father's mountainous presence at my side, beaming with pride. (19.19)
This is the biggest moment in Hassan's life. As everyone is applauding and admiring him, he imagines that his father, whom he always admired more than anybody else, is there with him. It's kind of like Hassan is admiring the memory of Papa, who is admiring him back.
"You have made me understand that good taste is not the birthright of snobs, but a gift from God sometimes found in the most unlikely of places and in the unlikeliest of people." (19.35)
After his big success, Hassan remembers Mallory stating the importance of looking up to others. Mallory has learned, or remembered, that you have to learn from others to grow. And it's probably a good guess that Hassan was a good example to her of this. A little admiration goes a long way.