Weekend cooking: sweet potatoes, garbanzo beans, and spinach soup

Here is a new soup concoction that I tried recently. I am a proponent of the high-fiber diet, so this is another high-fiber recipe. I usually cook huge batches of soups over the weekends and freeze portions for the work weeks ahead. 

Sweet potatoes, garbanzo beans, and spinach soup

You need:
2-3 Tbsp olive oil 
2 cans cooked garbanzo beans (15 oz)
1 package frozen chopped spinach (10 oz)
2 large sweet potatoes, peeled and chopped into small cubes
2 medium size onions, chopped into cubes
5 or more garlic cloves, chopped
2-3 stalks of celery, chopped
 
Instructions:
Soften the onion and celery in the oil. Add the garlic and cook for another five minutes. Add water (12 cups of water or to the desired by you density), bring to boil and add the potatoes. Cook to softness (approximately 10 minutes), add the garbanzo beans and the thawed spinach. Cook for another five minutes, turn off the heat and season with salt. Experiment with any spices you like – turmeric, black pepper, oregano, hot pepper flakes, paprika, mint, etc. 

How may I change the recipe? I did not add any spices except salt and found the soup a bit bland. Also, I do not have a sweet tooth. Instead of sweet potatoes, I will use red potatoes next time.