Defrost frozen berries on the counter for about 5 minutes. Break up any big clumps.
Pour berries into a small pot over medium heat. Add in water, maple syrup, and vanilla. Bring to a boil.
Then reduce heat to a low simmer for 10-12 minutes, stirring occasionally. Mash berries a little bit as you stir to break them up.
Remove from heat and stir in chia seeds and lemon juice. Taste and adjust for preference.
Let sit to thicken until cooled. Stir occasionally to make sure chia seeds are incorporated.