Pat the salmon dry. Season both sides with salt and pepper. Dry salmon sears better and gets a nice crust.
Make the sauce. In a small bowl, whisk soy sauce, low-carb sweetener or honey, rice vinegar, lime juice, minced garlic, ginger, and red pepper flakes.
Taste and adjust sweetness, acidity, and heat.
Cook the cauliflower rice. Heat 1 tablespoon oil in a large skillet over medium. Add cauliflower rice, a pinch of salt, and sesame oil if using. Sauté 4–6 minutes until tender with a bit of bite.
Transfer to bowls or keep warm.
Sear the salmon. In the same or a clean skillet, heat 1 tablespoon oil over medium-high. Place salmon fillets skin-side up first (if skin-on) and sear 2–3 minutes until golden. Flip and cook 2–3 more minutes.
Add the sauce. Lower heat to medium.
Pour the sauce around the salmon. Spoon it over the fillets as it bubbles and thickens, about 1–2 minutes. Cook until the salmon flakes easily but stays moist.
Remove from heat.
Build the bowls. Divide cauliflower rice into 4 bowls. Top with salmon, spoon over extra sauce, and add cucumber slices, avocado, green onions, and herbs. Sprinkle sesame seeds and add lime wedges.
Finish and serve. Taste and adjust—add more lime for brightness or a pinch of red pepper for heat.
Serve immediately.