Preheat the oven to 350 °F. Place a 12" cast iron skillet into the oven to preheat (if using a 13" x 9" baking pan you don't need to preheat the pan).
In a large bowl, combine 3 pounds fresh strawberries with juice from 1 lemon, ¼ tsp table salt and 6 oz granulated sugar. Toss to combine. Set the bowl aside for 30 minutes. Meanwhile, prepare the topping.
Combine 7 ½ oz all purpose flour, ¼ tsp salt, ½ tsp ground cinnamon, 3 oz brown sugar, 3 oz granulated sugar and ½ tsp vanilla extract in a large mixing bowl. Mix to combine the ingredients.
With the mixer running on low speed, toss in 6 oz unsalted butter slices and mix on until the the dough resembles wet sand and clumps together when squeezed. If you don't have a mixer the butter can be added by hand. Work the butter in with your fingers until it is broken down into bits smaller than a pea.
Toss the 1 tbsp corn starch with the the strawberries then pour them into the preheated 12" cast iron skillet or a 13"x 9" baking pan.
Grab a big handful of the topping and squeeze to form a large clump. Break the clump into smaller pieces over the strawberries. Continue to crumble the rest of the topping over the fruit in an even layer.
Slide the pan into the oven. Place a sheet of foil on the shelf beneath the cobbler in the oven to catch any juice boil over.
Bake until the topping is golden brown and baked in the middle and the juices are bubbling, about 30-35 minutes.
Serve warm or room temperature.
Notes
This recipe makes a big cobbler than can feed about 10-12 people. For a smaller group you can halve the recipe and bake it in an 8″ skillet or smaller casserole or cake pan.