Preheat olive oil in a large frying pan over medium high heat. Add in the onion and jalapeno and cook for 8 minutes to soften.
Add in the vinegar and spinach. You may need to add the spinach in batches so it wilts a bit before you add more. Stir and continue to cook until all the spinach is wilted.
Add in the ginger and garlic and cook 2 minutes. Add in the curry powder and cook 1 minute. Add in the coconut milk and stir to combine.
Pour the contents of the pan into a blender or food processor and pulse until it is a chunky sauce with no large pieces of spinach or stems intact.
Clean out the pan and preheat it with more oil. Add in the chicken, season with salt and pepper, and cook on high heat for 10 minutes to brown on all sides.
Pour in the sauce from the blender and bring to a simmer. Cook about 10 minutes until chicken is cooked through.
Serve with cauliflower rice.