• Toss the potatoes with a glug of oil, and sprinkle spices over the potatoes. If your spice jars have sprinkle lids, don't bother measuring - just sprinkle the spices with a light hand.
• Preheat oven to 425 degrees F. Line baking sheet with parchment paper (or silpat mat)
• Layer the the sweet potatoes and corn on the baking sheet (not the peppers).
• Bake for 30 minutes. At the 15 minute mark, give the potatoes and corn a gentle stir. Clear a space and add the chili peppers. Return to oven.

make the guacamole salsa

• While the vegetables roast, use a large fork to smash the avocado with a squeeze of lemon juice and lime juice, and a big pinch of salt. You want a fairly smooth (but not perfectly smooth) texture. Use more lemon and lime juice a squeeze at a time to break down the avocado. Taste often, until the guacamole is to your liking.
• Mix in the scallion and green chiles. Taste, and adjust with salt. Stir in the sour cream and mix until smooth and creamy.
• You want the guacamole salsa to be slightly thinned, so you can spoon it easily over the chips. Add just a drizzle of water, and mix well. Repeat until it falls easily from a spoon.

assemble

• Spread a layer of flat tortilla chips over a large serving plate, pizza pan, or rimmed baking sheet. Spoon about three-quarters of the salsa over the chips. Layer the sweet potatoes, corn, and green chiles over the chips. Add the remaining guacamole salsa, crumble the cheese generously over the chips, and top with cilantro. Serve at room temperature.