Authentic Oxtail Pho

Name: Authentic Oxtail Pho
Ingredients: water to cover; 1.5 pounds beef oxtail, or to taste; 2 Spanish onions, peeled, divided; 1 tablespoon fish sauce, or to taste; 1 tablespoon whole star anise pods; 1 cinnamon stick; salt to taste; 3 tablespoons beef pho flavor paste; 2 bunches scallions, chopped; 1 bunch fresh cilantro, chopped; 1 (16 ounce) package dried rice noodles, or to taste; 1 (12 ounce) package beef pho meatballs, halved, or to taste; 0.5 pound sirloin steak, thinly sliced, or to taste; 1 lime, cut into 8 wedges; 4 teaspoons white sugar, or to taste; 1 (8 ounce) package bean sprouts; 1 bunch Thai basil leaves, torn into bite-size pieces; 1 (2.8 ounce) can crispy fried shallots, or to taste