Prep Potatoes: Peel and chop potatoes into 1/2-inch pieces. Toss them in lime juice and water in a large bowl. Preheat oven to 415°F and line a baking sheet with parchment paper.
Season Potatoes: Combine cornmeal, chili powder, and salt. Toss the mix over potatoes, stirring to coat well. Shake off excess liquid and spread potatoes evenly on the baking sheet.
Bake Potatoes: Bake for 25-30 minutes until golden brown.
Cook Veggies: While potatoes bake, combine bell peppers, onions, chili powder, cumin, garlic powder, salt, lime juice, and water in a pan. Cook over medium heat for 8 minutes with the lid on, stirring occasionally, until tender and water has evaporated.
Remove Potatoes: Use a thin metal spatula to scrape and remove potatoes from the baking sheet immediately after baking.
Serve: Serve potatoes and veggies in bowls, tacos, or as a standalone dish. Top with avocado and Mexican tahini sauce.
Reheat Leftovers: To re-crisp leftover potatoes, reheat in the oven at 300°F for a few minutes.