Cut the chicken breast into bite-sized pieces and season with sea salt and black pepper.
Heat the coconut oil in a large skillet over medium-high heat and brown the chicken for 3-4 minutes until golden, then remove from the pan.
In the same skillet, add the finely diced onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic, grated ginger, and curry powder, cooking for 1 minute until highly aromatic.
Pour in the tomato puree and full-fat coconut milk, stirring to combine and scraping up any browned bits from the pan.
Return the chicken to the skillet, reduce heat to low, and simmer for 8-10 minutes until the sauce has thickened.
While the curry simmers, steam or sauté the cauliflower rice in a separate pan until tender.
Stir the fresh spinach into the curry during the last minute of cooking until just wilted.
Serve the warm chicken curry over the cauliflower rice.