Heat the oven to 425°F. Line two rimmed baking pans with parchment and place a small oven-safe dish nearby for the pepitas.

Toss the sweet potato rounds with 1 tablespoon olive oil, 1/4 teaspoon cumin, 1/4 teaspoon salt, and a few grinds of black pepper. Arrange in a single layer on one prepared pan.

Place the poblano peppers, tomatillos, onion wedges, and unpeeled garlic cloves on the second prepared pan. Drizzle with 1 tablespoon olive oil and season with 1/4 teaspoon salt.

Roast both pans for 18 minutes. Flip the sweet potatoes and rotate the vegetable pan, then continue roasting 8 to 12 minutes longer, until the sweet potatoes are browned at the edges and the poblanos are blistered and collapsed. Remove the sweet potatoes when tender and keep warm.

Transfer the poblanos to a bowl, cover with a plate, and let steam for 5 minutes. Peel off most of the loose skins, remove the stems and seeds, and squeeze the roasted garlic from its skins.

Blend the poblanos, tomatillos, onion, roasted garlic, crema, cilantro, 1 tablespoon lime juice, 1 tablespoon water, 1/4 teaspoon cumin, and a pinch of salt until smooth. Taste and adjust with more salt or lime juice; the sauce should be bright, smoky, and spoonable.

Lower the oven to 375°F. In a small bowl, mix the ancho chile powder, cocoa powder, smoked paprika, brown sugar, coriander, 1/4 teaspoon salt, and a few grinds of black pepper.

Pat the salmon dry and place it in a lightly oiled small baking dish. Stir the honey with 1 tablespoon lime juice and brush it over the tops of the fillets, then press the ancho-cocoa spice blend evenly over the salmon.

Bake the salmon for 10 to 14 minutes, depending on thickness, until the spice crust looks set and the thickest part flakes gently while remaining glossy in the center. Rest the salmon for 3 minutes.

While the salmon rests, place the pepitas in the small oven-safe dish and toast in the oven for 3 to 5 minutes, until fragrant. Toss with lime zest and a tiny pinch of salt.

Spoon poblano crema onto two warm plates. Arrange the roasted sweet potato rounds alongside, set the salmon on top or beside them, and finish with cotija, lime-zested pepitas, cilantro, pickled red onions, and lime wedges.