Heat vegetable oil in a large pot. Add in garlic, ginger, and scallions. Cook for 2-3 minutes, then add pork. Break up pieces with back of your spoon and cook until lightly browned.
Stir in chicken broth and bring to a light simmer. Add tofu, mushrooms, sugar, rice vinegar, soy sauce, pepper, and sesame oil and sriracha. Bring to a boil and cook for 5-10 minutes, tasting and adjusting seasoning (add more vinegar if you want it to be more sour or more sriracha to increase heat).
Next, slowly pour in beaten eggs, stirring vigorously so they form strands in soup and don't all lump together.
Serve with some scallions and a little sesame oil on top.
Recipe by Things I Made Today at https://www.thingsimadetoday.com/2013/10/02/chinese-hot-sour-soup/