Preheat oven to 400 degrees F. Drain the chickpeas, rinse, and pat dry. Transfer them to baking sheet, drizzle with oil, and toss. Sprinkle with the 1/4 tsp each cumin, chili powder, and salt. Toss again, and bake for 15 minutes.
Meanwhile, heat a large skillet over medium heat with the oil while you slice the onions. Add them to the skillet along with the seasonings. Stir to incorporate the seasonings.
After 5 min cooking (you can add a tablespoon or two of water to the pan during this process if getting too dry), add red cabbage and bell peppers. Cook another 5 min w/lid on, stirring occasionally.
Add in corn, cook just until peppers are crisp-tender.
Make the guacamole by mashing the avocado in a bowl, and add in the other guacamole ingredients, and stir well.
Heat the tortillas by gently toasting in a skillet or warming in the microwave for approx 20 to 30 seconds.
While those are heating, make the spicy tahini sauce by whisking together the ingredients in a bowl.
Assemble by dividing the chickpeas and vegetables between the warmed tortillas. Then, top with guacamole and spicy tahini sauce (you may have a bit of extra tahini sauce to use for another recipe).