Tom Kha Gai (Thai Coconut Soup)

1 tbsp coconut oil
1 onion, sliced
4 cloves garlic, roughly chopped
2 in fresh ginger, peeled and sliced into rounds
1 stalk lemongrass, pounded with the side of a knife and cut into 2-inch long pieces OR 2 tbsp lemongrass paste
2 tsp red Thai curry paste
6 cups chicken bone broth (OR vegetable broth if vegan)
2 cans coconut milk, (I use Simple Native Forest)
1lb boneless skinless chicken thighs, cut into bite-sized pieces (discard if vegan)
4 carrots, peeled and sliced into rounds
8 oz mushrooms, sliced if larger (pick your favorite mushroom, I use shimeji)
2 tbsp coconut sugar (OR coconut aminos if on Whole30)
2 tbsp Red Boat fish sauce, plus more to taste
1-2 limes, juiced