Place all ingredients in a large bowl and toss to coat. Pour the mixture onto a large baking sheet lined with parchment paper. Roast the beans and corn for 15 minutes.
Place all Avocado Ancho Dressing ingredients in a large food processor. Blitz until smooth. Pour the finished dressing into a bowl, jar or bottle and refrigerate until ready to use.
Grease a BBQ grill or cast iron grill pan with the olive oil. Heat the BBQ grill or grill pan over high heat until smoking.
Place the lettuce cut side down on the grill or grill pan. Grill the lettuce for 2 minutes. Take it off of the heat immediately.
Place half a head of lettuce on each of four plates. Drizzle each lettuce half with Avocado Ancho Dressing.
Top with a healthy scoop of the Roasted Corn and Beans. Sprinkle each half with jalapeño slices, Fritos, cilantro, and red onion. Serve immediately.