Heat olive oil in a stockpot or deep skillet over medium heat. Add sausages and brown on all sides. Transfer to a plate lined with a paper towel. When cool enough to handle, cut in 1/4-inch slices.
Add onion to pot and saute until softened, 3-4 minutes. Add squash, garlic and peppers. Saute 3 minutes. Add dry spices and cook, stirring, 1 minute. Add tomatoes, chicken stock, tomato paste, Sriracha and bay leaf. Simmer until squash is tender, about 20 minutes. Stir in black beans, sausage, salt and pepper. Simmer 10 more minutes. Taste to adjust seasoning.
Before serving, add cilantro. Serve in bowls garnished with additional cilantro, chopped avocado and a drizzle of sriracha.
(Chili may be made up to 24 hours in advance. Cool, cover and refrigerate. Re-warm over medium heat to serve.).