In a large bowl combine the chicken cubes, chopped red onion, minced garlic, ground ginger, cinnamon, allspice, garam masala, turmeric, paprika, chili flakes, chopped mint and parsley, lime juice, 2 tablespoons plain yogurt, 1/2 teaspoon salt, and 1 teaspoon black pepper; toss well to coat and let marinate 5–10 minutes while you prepare the rest.
Make the cilantro-corn slaw: in a bowl, combine shredded cabbage, shredded carrots, sliced radishes, and chopped fresh cilantro; toss and set aside.
Prepare the yogurt sauce by stirring 3/4 cup plain yogurt with the juice of 1 lime, a pinch of salt, and 1/4 cup chopped mint and parsley; refrigerate until ready to serve.
Heat a cast iron skillet or griddle over high heat and add 1 teaspoon olive oil; when the pan is very hot, add the marinated chicken in a single layer.
Leave the chicken undisturbed for 2 minutes to develop a char, then toss or turn the pieces and cook another 2 minutes; reduce heat to medium and continue cooking, stirring frequently, until the chicken is cooked through, about 3 more minutes.
Warm the mini tortillas, then assemble tacos by layering slaw on a tortilla, topping with several pieces of tandoori chicken, sliced avocado, a few radish slices, a squeeze of lime, and a dollop of the yogurt sauce; garnish with fresh cilantro leaves.
Serve immediately and enjoy.