Sweet Potato, Sausage, & Kale soup

This is my version of a recipe I found.

1-2 Tb. olive oil
1 lg. onion, chopped
1 tsp. salt
1/4 tsp. fresh ground pepper
1/4 tsp. crushed red pepper (may want to omit if using a spicy sausage)
3 garlic cloves, minced
1 lb. kielbasa sausage, chopped (can use less)
5 c. sweet potato, peeled & chopped
2 c. water
1 qt. chicken stock
1 bunch kale, washed and torn
1 can cannellini beans or white beans, drained and rinsed

Heat oil in a large soup pot over medium-high heat. Add onion and saute until tender and almost translucent. Add salt, pepper, red pepper, and garlic. Cut sausage into bite size pieces and add to pan. Cook until sausage is lightly browned. Add sweet potato, water, and broth and bring to a boil. Reduce heat and simmer 8 minutes. Gradually add kale and cook until tender. Stir in beans and cook until thoroughly heated.