Prepare the Base: In a medium pot, bring water to a boil. Add salt, ground flax seeds, and coriander to the water, stirring to combine.
Add the Barley: Gradually whisk in the ground barley to avoid lumps, then reduce the heat to a simmer. Continue stirring regularly to prevent sticking.
Cook Until Thickened: Allow the mixture to cook for 20–25 minutes, stirring occasionally, until it reaches a porridge-like consistency.
Serve and Top: Once the polenta is thick and smooth, remove it from the heat and let it rest for a few minutes. Serve warm, topping with peach slices, a drizzle of honey, and a handful of chopped walnuts.