Heat olive oil in a large pot or Dutch oven over medium heat.
Add the diced onion and minced garlic to the pot. Sauté until the onion becomes translucent and the garlic becomes fragrant, about 5 minutes.
Add the cubed butternut squash to the pot. Sauté for another 5 minutes, allowing the squash to slightly soften.
Add the soaked and drained black beans, vegetable broth, cumin, smoked paprika, dried oregano, bay leaves, salt, and black pepper to the pot. Stir well to combine.
Bring the mixture to a boil, then reduce the heat to low. Cover the pot and let the stew simmer for about 30-40 minutes, or until the beans and squash are tender.
Remove the bay leaves from the pot and discard them.
Using a potato masher or the back of a spoon, gently mash some of the beans and squash against the side of the pot. This will help thicken the stew and create a creamier texture.
Taste the stew and adjust the seasoning with salt and black pepper, if needed.
Serve the black bean butternut squash stew hot, garnished with fresh cilantro, sliced avocado, and lime wedges on the side.