Preheat the oven to 250°F.
Line a baking sheet with parchment paper and set aside.
In a small bowl, whisk together the sugar and cornstarch.
Add the egg whites to the bowl of a stand mixer fitted with the whisk attachment (or a handheld beater using a large bowl). Add the pinch of salt, and begin to beat the eggs on a medium-low speed until frothy, then, turn the mixer speed up to medium-high and beat until soft peaks form.
While the mixer is running, begin adding the sugar/cornstarch mixture slowly, about 1 Tbsp at a time, until all the sugar has been added.
Continue to beat until the egg whites are thick and glossy and stiff peaks are formed (when the whisk is turned upside down, the meringue should hold a peak and only droop back on itself a tiny little bit). It's also important to ensure the sugar has dissolved. To check this, rub a small amount of the meringue between two fingers. If it's girtty, it needs more time to allow the sugar to dissolve. Scrape down the sides.
Add in a tiny dot of gel food colouring, if using. Add vanilla. Sift in the strawberry powder and whisk until just combined and evenly mixed.
Using a small ice cream scoop (mine is about 2 1/2 Tbsp), scoop 12-14 heaping balls of meringue onto the parchment lined baking sheet.
Place the baking sheets in the oven and bake for 50 minutes. The insides will still be chewy, which is how I like them. If you want your meringues to be more crispy, bake for 1 hr 10 mins.
Turn the oven off, and crack the door to allow steam to release. Keep the oven door open slightly. Keep the meringues in the oven while it’s turned off for about an hour.
Melt the chocolate in a heatproof bowl in the microwave in 15 second increments until fully melted. Allow to cool slightly. Dip the bottoms of each meringue in the chocolate and place back on the parchment to dry fully.
Store in an airtight container for up to 7 days.