1. To make chutney, soak red chiles in 2 cups hot water for 30 minutes. Drain, reserving 1/4 cup soaking liquid, then stem, seed, and dice chiles. Combine chiles and reserved soaking liquid in a blender and blend until smooth. Heat oil in a medium saucepan over medium heat. Add red onion and cook until soft, about 5 minutes. Add garlic and cook for 30 seconds. Add red chile puree, bring to a boil, and cook until slightly thickened, about 5 minutes. Add tomatoes and oregano and cook until slightly softened, about 10 minutes. Stir in honey and season with salt and pepper. Remove chutney from the heat and fold in green onions. Serve warm or at room temperature.
2. Whisk together sour cream, yogurt, garlic, lime zest, lime juice, ancho powder, coriander, cumin, turmeric, and chile de arbol powder in a baking dish. Add salmon fillets and turn to coat. Cover and refrigerate for at least 20 minutes and up to 1 hour.
3. Heat grill to high. Remove salmon from marinade and wipe off excess with paper towels. Brush salmon on both sides with 1 tablespoon oil and season with salt and pepper. Grill until golden brown on both sides and cooked to medium, about 4 minutes per side.
4. Meanwhile, brush cut side of limes with remaining 1 teaspoon oil and put on the grill, cut-side down, until browned, about 1 minute.
5. Transfer salmon to plates and garnish with green onion. Add a lime half to each plate for squeezing over salmon and serve chutney on the side.