Prepare the Puree: In a small saucepan, combine the blueberries, lemon juice, zest, and water. Cook over medium heat for 5-7 minutes, until berries burst. Remove from heat and let it cool completely. For an ultra-smooth pudding, blend the cooled mixture. You should have about $1/2$ cup of puree.
Mix Wet Ingredients: In a medium bowl or jar, whisk together the almond milk, the $1/2$ cup of cooled blueberry puree, maple syrup, and vanilla extract. Whisk until fully blended.
Incorporate Chia Seeds: Add the chia seeds to the mixture. Whisk vigorously for about 30 seconds. This is the first critical step to prevent clumping.
The Second Whisk: Wait 5 minutes, then whisk the mixture thoroughly one more time. This ensures all the seeds are suspended and beginning to absorb the liquid evenly.
Chill: Cover the bowl/jar and place it in the refrigerator for at least 4 hours, or preferably overnight, until the pudding has thickened to a gelatinous consistency.
Serve: Stir the pudding before serving. Garnish with fresh blueberries, a thin lemon slice, or a sprinkle of toasted almonds.