Slice the garlic, fennel, carrot and pepper. Snap off the end of the asparagus.
Heat a little oil in a lidded casserole dish, add the fennel seeds. Stir for a few seconds, then add the fennel, garlic, carrot and pepper slices. Put the lid on and gently sauté them for 10 minutes until soft.
Now add the broccoli and asparagus stems. Put the fish on top. Sprinkle with lemon zest, drizzle with the lemon juice. Season to taste with salt and pepper.
Put the lid on and gently braise for about 10 minutes until the fish is just cooked through.