Finely chop the strawberries and discard the stalks. Finely grate the lemon zest with the small side of a box grater. Add the strawberries, lemon zest, cashew butter, and yogurt to a large bowl and stir to combine.
If you have silicone mold trays, spoon in the filling and scrape the tops flat. Freeze for at least 1 hour, depending on the size and depth of your molds, until set. If you do not have molds, either use ice cube trays or spoon out portions onto a tray lined with baking paper.
Break up the dark chocolate into small pieces. Place the dark chocolate and coconut oil in a glass or metal bowl over a saucepan with 1 inch of water (use a bain-marie or double boiler). Take care not to let water touch the bottom of the bowl, as this will burn the chocolate. Bring the water to a simmer over medium heat and let the chocolate melt to a silky smooth consistency, stirring occasionally. Remove from the heat.
Line a baking tray with baking paper and have it ready near the chocolate. Pop the frozen yogurt pieces out of their molds.
One at a time, drop a yogurt cluster into the melted chocolate. Use 2 spoons to turn the cluster and quickly place it onto the tray. The chocolate will set very quickly. Repeat until all the yogurt pieces are covered. Drizzle any remaining chocolate over the tops for presentation points!
Return to the freezer for 10 minutes to set fully. Enjoy whenever you want a treat!