Preheat oven to 180°C or 160°C fan forced. Line a tray with baking paper. Place mushrooms onto prepared tray.
Heat oil in frying pan over medium to high heat. Add shallots and stalks, and fry for 1 minute. Add brown rice and fry for a further minute. Add 2 tablespoons water and tamari. Stir to coat.
Spoon mixture into mushroom cases. Bake for 15-20 minutes till golden.
Blend avocado and coconut cream in a small spice blender, or mash with a fork. Serve mushrooms topped with avocado cream, beans, coriander leaves, red chillies. Serve with fresh lime wedges.