Prepare the ingredients: Marinate the pork bones with 1/2 teaspoon salt, 1/2 teaspoon chicken bouillon powder, 1/2 teaspoon sugar, and 1 tablespoon annatto oil. Cut the tomatoes into wedges. Finely chop the onion and garlic.

Strain the crab: Add water to the ground crab and strain through a fine mesh sieve. Repeat until the crab liquid is clear and no longer cloudy.

Cook the crab broth: Pour the strained crab liquid into a pot and cook over medium heat until the crab forms curds on the surface. Use a skimmer to gently remove the crab curds and place them in a bowl with the ground pork. Take enough crab curd to mix with the pork to form a mound, but leave some small curds in the broth for extra flavor. Add the pork bones to the broth and simmer until the bones are tender.

Sauté the tomatoes: Heat annatto oil in a pan and sauté the chopped onion and garlic until fragrant. Add half of the tomato wedges and cook until they soften and develop a nice color.

To serve: Place rice vermicelli noodles in a bowl. Add tomatoes, tofu, pork bones, a portion of the steamed crab mixture, and green onions on top. Ladle the hot broth over everything. Serve with fresh herbs and fermented shrimp paste for authentic flavor. Now you have a delicious, nutritious, and affordable bowl of bún riêu cua, just like at a restaurant!