Thaw strawberries and drain pineapple in advance if needed.
If needed, use processor to chop walnuts slightly smaller than pea-size. Put walnuts in mixing bowl.
In a food processor, pulse cranberries until pieces are about pea-sized. Add pineapple and strawberries and pulse a few more times until everything is about the same size.
Remove blade from processor and stir in chia and 2 T maple syrup. Stir, taste and add additional maple syrup to achieve desired sweetness.