Preheat oven to 350 degrees. Line a baking sheet with parchment paper. Grease either 6 jumbo muffin tins or 12 regular muffin tins (or line with muffin liners). Set aside.
Place the quartered strawberries on the lined baking sheet and sprinkle with 1 teaspoon of sugar. Roast for 25 minutes. Remove from oven and allow to cool for about 5-10 minutes.
In a large bowl, whisk together the flours, sugars, salt, and baking soda. Add the starter, melted butter, beaten egg, vanilla, and buttermilk. Whisk together until just combined. Fold in the roasted strawberries and pecans.
Fill prepared tins with the batter. Top each muffin with 2-3 slices of fresh strawberry. Bake for 25-35 minutes for jumbo muffins or about 20 minutes for regular muffins, or until a toothpick inserted into the center comes out clean. Allow to cool for a few minutes before removing from the tins to cool on a rack.