Add the strawberries, sugar-free sweetener, and sea salt to a small saucepan, cover, and heat over medium heat. Bring this mixture to a full boil. Stir the strawberry mixture occasionally and allow it to continue to cook at a gentle boil until the strawberries have leached out a great deal of moisture and a lot of liquid forms. Add the tapioca flour and continue cooking, mashing the strawberries as you stir, until the mixture is very thick, about 20 minutes total. Remove from heat and set aside or refrigerate until ready to use.

While the strawberry mixture is cooking, prepare the rest of the recipe.

Preheat the oven to 350 degrees F and line a 8” x 8” cake pan with parchment paper.

Prepare the Crust: 

Stir together all of the ingredients in a mixing bowl. Keep stirring until a thick, moist, crumbly dough forms.

Measure out ½ cup of the crust mixture and place it in a bowl to use as the topping. 

Press the rest of the crust mixture into the parchment-lined cake pan until you have an even layer of crust. Poke several times with a fork to ensure even baking. Bake on the center rack of the preheated oven for 12 to 16 minutes, or until the crust is golden-brown and appears as though it has set up. 

Remove the crust from the oven.

Spread the strawberry filling mixture over the crust in an even layer. Sprinkle the reserved topping mixture over the strawberry layer. 

Bake the bars for 20 to 25 minutes, or until the crumb bar topping is golden-brown. Remove from the oven and allow crumb bars to cool at least 30 minutes before slicing and serving.

Note: I chill the bars in the refrigerator to allow them to cool completely before slicing.