📖 Instructions

1. Before anything else, preheat your oven to 400°F (200°C). This ensures it's piping hot and ready to give your muffins that initial burst of heat, helping them rise beautifully. While it's heating, line a 12-cup standard muffin tin with paper liners. If you don't have liners, you can grease the wells really well, but liners make cleanup a breeze!
2. In a large bowl, whisk together all your dry ingredients: the all-purpose flour, granulated sugar, baking powder, baking soda, salt, and ground cinnamon. Whisk for about 30 seconds to a minute, making sure everything is really well combined and there are no lumps of baking powder hiding out. This even distribution is key for a consistent rise.
3. In a separate, medium-sized bowl, gently whisk your wet ingredients. Start with the large egg, then add the buttermilk, the melted unsalted butter (make sure it's cooled a bit so it doesn't scramble your egg!), and the vanilla extract. Whisk until everything is just combined and looks smooth. Don't go crazy here, just enough to mix.
4. Now for the magic moment: slowly pour the wet ingredients into the dry ingredients. Grab your rubber spatula and mix until they are *just* combined. And I mean *just*. A few lumps in the batter are not only okay, they're actually preferred! Overmixing is the arch-nemesis of a tender muffin, leading to a tough, chewy texture. Stop mixing as soon as you don't see any streaks of dry flour.
5. Time for the stars of the show! Gently fold in your chopped fresh strawberries and chopped fresh rhubarb. Use that rubber spatula and fold carefully, ensuring the fruit is evenly distributed throughout the batter without squishing it too much. You want those lovely chunks in every bite.
6. Divide the batter evenly among the 12 prepared muffin cups. A large ice cream scoop works wonders for this, making the process cleaner and ensuring uniform muffin sizes. Fill each cup about two-thirds full.
7. For an extra touch of sparkle and a slight crunch, sprinkle about 1/2 teaspoon of turbinado sugar over the top of each muffin. This is totally optional but adds a lovely professional finish and a little extra texture.
8. Place the muffin tin into your preheated 400°F (200°C) oven. Bake for an initial 5 minutes. This high heat blast helps them puff up nicely, creating those desirable domed tops. After 5 minutes, without opening the oven door too long, reduce the oven temperature to 375°F (190°C).
9. Continue baking at the lower temperature for another 18-22 minutes, or until a wooden skewer or toothpick inserted into the center of a muffin comes out clean or with just a few moist crumbs attached. The tops should be beautifully golden brown. Keep an eye on them, as oven temperatures can vary!
10. Once baked, carefully remove the muffin tin from the oven. Let the muffins cool in the tin for about 5 minutes. This brief cooling period helps them firm up and makes them easier to remove. After 5 minutes, transfer the muffins to a wire rack to cool completely. Or, if you're like me, grab one while it's still warm – just be careful, the fruit will be hot!