In a medium-sized skillet, heat olive oil over medium heat. Add the diced onion and minced garlic, and sauté for 2-3 minutes until the onion becomes translucent.
Add the black beans, ground cumin, chili powder, salt, and pepper to the skillet. Cook for another 5-7 minutes, stirring occasionally, until the beans are heated through and well-seasoned. Adjust the seasoning to taste.
In a separate bowl, combine the diced tomatoes, diced red onion, chopped cilantro, lime juice, matcha powder, salt, and pepper to make the matcha-infused salsa. Mix well until all the ingredients are evenly incorporated.
Warm the corn tortillas in a dry skillet or on a griddle until soft and pliable.
Assemble the tacos by filling each tortilla with a spoonful of the seasoned black beans, a few avocado slices, and a dollop of matcha-infused salsa.
Add any desired optional toppings, such as diced tomatoes, shredded lettuce, chopped cilantro, vegan sour cream, or a squeeze of fresh lime juice.
Serve the Matcha Black Bean Tacos warm and enjoy!