Slice red onion into thin slices. Line a medium pot with 1/4 cup of water and cook onions over high heat until translucent, about 3 minutes. Add broth, yam, 3/4 cup water and bring to a boil. Once boiling, reduce to medium and cook until potatoes are almost fork tender, about 3 minutes. Immediately add kale and remaining ingredients and cook, stirring frequently, until kale is dark green and soft, about 3 more minutes. Set aside for 5-10 minutes, allowing flavors to merge.