In a medium mixing bowl, whisk together the rolled oats, chia seeds, ground flaxseed, cinnamon, turmeric, black pepper, and salt.
In a separate bowl or jar, whisk the almond milk, Greek yogurt, honey, and vanilla extract until smooth and no yogurt clumps remain.
Pour the wet mixture into the dry ingredients and stir well, until no dry pockets of oats or chia are left.
Divide the mixture evenly between two 250 ml / 8 oz jars, filling each about two-thirds full.
Cover the jars and refrigerate for at least 6 hours, or overnight, until the oats are softened and the mixture is thick and spoonable.
Before serving, stir each jar to loosen the oats. If it looks too thick, stir in a splash of extra milk.
Top each jar with half the mixed berries and chopped walnuts. Drizzle with extra honey if you like, and eat cold straight from the fridge.