Boil a pot with ½ cup water + pinch of salt; add beans to boiling water, cover + steam til tender, about 3-4 min; drain, season with salt/pep + a drizzle of oil; divide between bowls

Meanwhile, wipe mushrooms clean + slice; heat 1 tbsp oil in skillet over high, add mushrooms + cook undisturbed 3 min; sauté 3-4 min more til tender, season with salt/pep + divide between bowls

Pat fish dry + season with salt/pep; heat 1 tbsp oil in skillet over med-high (get that pan hot, otherwise fish will stick); sear skin-side down 5-6 min til fish releases from pan; flip + cook 1-2 min til cooked through

Top bowls with barramundi then dollop each with 2 tbsp sauce