Soak the ancho chile in water overnight or in hot water for at least 1 hour, until pliable.
Preheat the oven to 400°F.
On a baking sheet, toss the onion, garlic, and tomato with 2 tablespoons olive oil and a pinch of salt and pepper. Roast until beginning to caramelize, about 15 minutes. Transfer the roasted vegetables to a blender, along with the almonds, roasted red peppers, sherry vinegar, and honey. Blend until smooth. With the motor running, drizzle in the remaining 1/2 cup oil until emulsified. Season to taste with salt and pepper.
Reduce the oven to 375°F
Bring a large pot of salted water to a boil. Add the orzo and cook according to package instructions. Drain the orzo, return to the pot, and toss with the peas, spinach, lemon juice, lemon zest and dill.
Dry the salmon with paper towels and sprinkle the fillets with salt and pepper. Heat a large skillet or grill over medium heat with 1 tablespoon oil and when hot, add the salmon skin side-up. Sear until golden brown, then transfer to a baking sheet and finish cooking in the oven for 8-10 minutes.
To serve, divide the orzo and salmon between plates. Top with romesco sauce.