In a large pot, heat the vegetable oil over medium-high heat, add the garlic and onion, and sauté until translucent, about 10 minutes.
Add the tomatoes and continue to cook until the tomato juice is reduced by ½, about 20 minutes.
Meanwhile, use a damp towel to rub the chiles in order to clean them. Add the cleaned chiles, black beans, the water, and the chicken stock to the pot and bring to a boil.
Reduce the heat to medium and simmer the soup until the beans are falling apart tender and the soup has thickened slightly, about 3 hours.
After simmering, add the avocado leaf powder and stir to combine. Using a hand blender, carefully purée until smooth. Season with salt, to taste, and garnish with the red onion, sesame seeds, crema, avocado, tortilla chips, and ancho powder before serving.
*Note: Avocado leaf powder is made from grinding dry avocado leaves, which can be found at most specialty Latin markets.