Drain the tofu, then cut it into large cubes. Place the cubes in a shallow baking pan and set aside.
In a small mixing bowl, combine the olive oil, vinegar, cumin and chilli powder, and mix well. Pour the olive oil and marinade over the tofu cubes and let them sit for at least 1 hour.
In a large salad bowl, lightly toss the chopped onions and diced tomatoes and avocado pieces, and mixed salad greens. Top the salad with the marinated tofu and garnish with blue corn tortilla chips.
Tips
Also use Extra Firm tofu depending on your preference of softness