First, make the Walnut Salsa Seca: In a wide-bottomed sauté pan, warm the oil over medium heat and toast the guajillo chilies until aromatic, about 2–3 minutes. Strain the oil into a medium mixing bowl and set aside.
Place chilies and all the seeds into a food processor and pulse until uniform.
Transfer the mixture into the bowl with the chili oil. Stir in walnuts, orange chips, and puffed rice. Season to taste with salt.
To make the corn: On a gas or charcoal grill heated to medium, place ears of corn on grates. Cook 2 minutes or until slightly charred on one side. Rotate corn a quarter turn, cook another 2 minutes or so, and repeat until charred evenly. When all the corn is charred to your liking, remove to a dish. If not serving immediately, cover with aluminum foil to keep warm.
Arrange corn architecturally, some standing on end, some laid on their sides. Spoon the Walnut Salsa Seca over the top of the corn, allowing some to pile up and some to fall to the plate. Squeeze fresh lime and drizzle olive oil over the top of the corn as desired. Garnish with fresh oregano.