Heat a drizzle of olive oil in a large Dutch oven. Add the onion and cook until tender. Add the celery, carrot and garlic. Cook until fragrant and beginning to soften.
Add the red pepper, chipotle chillies, cumin, oregano and paprika. Cook for a few minutes, coating all the veg well in the spices.
Pour in the tinned tomatoes, all the drained legumes and the stock. Bring to a simmer.
Simmer on low heat for 30 minutes to bring all the flavours together and reduce slightly. Add a little stock or water if you reduce it too much. Taste to adjust seasoning.
While the chilli cooks prepare the mushrooms. Slice mushrooms into quarters. Heat a drizzle of olive oil in a large frying pan. Add the mushrooms and cook until they release all their water and are golden brown.
Just before finishing add the cumin and paprika. Toss to coat well.
When the chilli has sufficiently simmered add the mushrooms and stir through to combine. Taste to adjust seasoning
Serve generous spoonfuls of mushroom chilli over brown rice. Top with fresh coriander, avocado and pickled onions.