Prep the base: In a food storage container or medium bowl, combine Greek yogurt, soy milk, maple syrup, and vanilla extract until smooth.
Mix in chia: Pour into a large jar or container, whisk in chia seeds, and let sit for 5–10 minutes. Stir again to prevent clumping.
Chill & serve: Refrigerate for at least 4 hours or overnight until thickened. Separate into 4 containers. Serve topped with thawed mango (optional: blend the thawed mango for a puree consistency) and extra yogurt, toasted coconut or slivered almonds if desired.
Store: Cover with silicone covers or store in jars in the fridge for up to 5 days.