Season salmon fillets with salt and pepper. Heat 1 tablespoon olive oil in a skillet over medium-high heat. Sear salmon, skin side down if using skin-on, for 3–4 minutes until crispy. Flip and sear the other side for 2–3 minutes. Remove salmon and set aside.
Reduce heat to medium and add butter to the skillet. Stir in minced garlic and sauté for 1–2 minutes until fragrant, being careful not to burn it.
Add chopped onion and sliced red bell pepper. Sauté for 3–4 minutes until softened.
Stir in red curry paste and cook for 1 minute. Add coconut milk, soy sauce, and honey or maple syrup. Simmer for 4–5 minutes until slightly thickened. Adjust seasoning with salt, pepper, or lime juice.
Place seared salmon back into the skillet. Spoon sauce over the salmon and simmer for 2–3 minutes to absorb flavors.
Sprinkle chopped cilantro over the top. Serve salmon and sauce over cooked rice or cauliflower rice.