Preheat oven to 350 degrees (F). Lightly grease a doughnut pan; set aside.: You should feel gentle warmth in the kitchen as the oven comes up to temperature, and you may notice a faint oven scent when it reaches heat. Preheating ensures even rise, because a cold oven will delay leavening and make the center dense. If you skip greasing, the donuts can stick and tear when you remove them. Test for doneness visually, looking for a pale golden top rather than a deep brown; that indicates the interior has set while remaining tender.
In a large bowl whisk together the dry ingredients. In a separate bowl whisk together the sour cream, melted butter, and egg. Gently fold the wet mixture into the dry mixture until just combined - don't over mix! Gently fold in crushed strawberries.: As you whisk the dry components, you will smell a neutral, slightly bready scent from the flour . When the wet mix blends in, the batter should look uniform but still slightly lumpy, with ribbons of cream and flecks of crushed strawberries . Over mixing activates gluten, which makes donuts tough rather than tender. A common error is vigorous stirring; avoid this by using a spatula and folding with care. Stop folding when streaks disappear, and then fold in the dried fruit gently so it disperses without crushing completely.
Spoon mixture into prepared doughnut pan, and bake for 10 minutes, or until the doughnuts spring back when lightly pressed. Allow doughnuts to cool completely in the pan before frosting.: When you spoon batter into the pan, listen for the slight thump of batter against metal and aim for even fills so donuts bake uniformly. During baking the kitchen will fill with a warm baked flour and butter aroma, and the tops should become just a touch golden. The spring back test tells you the interior is set; if they sink when touched, they need more time. Cooling in the pan prevents breakage while transferring; removing them too soon can cause them to collapse. Patience here keeps the texture airy rather than gummy.
Combine heavy cream and confectioners' sugar in a medium-sized bowl. Whisk smooth, adding a touch more cream if the frosting seems too thick; adding a touch more sugar if the frosting seems too thin. Mix in salt and dried berries.: As you whisk, the glaze moves from powdery to glossy; the sound becomes a smooth, steady whisk rather than a stiff scrape. The right consistency should coat a spoon and slowly fall back in ribbons. Adding cream too fast makes the icing runny and it will slide off the donuts, while too little keeps it clumpy. Stir in the crushed strawberries last so their aroma is fresh and they do not rehydrate and make the glaze grainy.
Once the donuts have cooled completely, spread the frosting over the tops of each and decorate with extra dried berries if desired.: The final step is tactile and visual, as the cool donuts meet the glossy glaze and the crushed strawberries add a bright flecked finish. Use a small offset or spoon to spread so each donut looks clean and polished. If the glaze slips off, it may be too thin or the donuts were not fully cooled; let them rest a few more minutes. Arrange them on a platter while the glaze sets to avoid smudging, and enjoy the contrast of tender crumb and crisp dried fruit on top.