Lightly spray the halibut fillets with avocado or olive oil. Sprinkle them evenly with smoky Sriracha seasoning, citrus pepper, and a pinch of salt. Rub the spices all over the fish to ensure the flavors are well-distributed. Set aside to allow the seasoning to infuse.
Heat a large nonstick skillet over medium-high heat and spray it with oil. Add the sliced bell peppers and onion to the skillet, seasoning them with a pinch of sea salt and pepper.
Cook for 5–7 minutes, stirring occasionally, until the peppers are tender, and the onions are lightly browned and translucent. If your skillet is small, cook the veggies in batches. For faster cooking, cover the skillet for 1–2 minutes to help the vegetables soften, then uncover and toss until they are evenly cooked.
Remove the veggies from the skillet and set them aside, keeping the skillet on the heat.

Spray the skillet lightly with oil again and add the seasoned fish fillets. Cook on both sides until the fish is cooked through and the edges are seared, about 3–4 minutes per side, depending on the thickness of the fillets.
Just before removing the fish from the skillet, squeeze fresh lemon or lime juice over the fillets to enhance their flavor. Transfer the cooked fish to a plate and use a fork to flake the fillets into bite-sized pieces, making them perfect for assembling fajitas.
In a small bowl, whisk together the Greek yogurt and red enchilada sauce. This creamy, tangy sauce will be the finishing touch for your fish fajitas recipe.
Lay a low-carb wheat tortilla flat and layer it with sautéed fajita veggies, flaked fish, pickled cabbage (optional), and a generous drizzle of the yogurt enchilada sauce. Garnish with fresh cilantro for a pop of flavor and color.
Serve immediately and enjoy the fresh, zesty flavors of your homemade fish fajitas recipe!

If you’re making these for meal prep, store the tortillas and sauce separately from the fish and veggies to prevent sogginess. This dish will keep in airtight containers in the fridge for 3–4 days.