Preheat the oven to 350 degrees Fahrenheit. Line a baking sheet with parchment paper.
Cube and roast the potatoes and sweet potatoes:
Peel and cut the potatoes and sweet potatoes into small dice. Toss with enough olive oil to generously coat, along with salt and pepper to taste.
Spread the diced potatoes and sweet potatoes in a single layer on the prepared baking sheet. Bake until tender and beginning to brown on some corners, 20 to 25 minutes, tossing once or twice partway through.
Heat the mole and prepare the garnishes:
In a small pot (or in the microwave, if you want to cheat), gently warm the 1 cup of mole until it’s hot.
As the mole heats, crumble the 2’’ by 1’’ piece of cotija and pluck the cilantro leaves from the stems.
Plate and serve:
Pour 1/4 of the mole into the center of each of four plates, then tilt (or spin) each plate to spread the mole into an even circle.
On each plate, arrange 1/4 of the roasted vegetables in a crescent shape around the edge of the mole. Sprinkle with 1/4 of the crumbled cotija and cilantro leaves.