Microwave the chips and coconut oil in the tall cup at 50% power for 30 seconds, then stir. Repeat 3 to 4 times, about 2 minutes in all, until only a few soft chips remain. Stop there so the chocolate stays under 115°F, then stir until it looks smooth and glossy.

Hold a berry by the stem, dip it at a slight angle to cover two thirds of the fruit, then lift straight up and twist gently. Drag the tip across the cup rim once, then hold the berry over the cup for 5 seconds, until the drip slows to a trickle.

Set each berry on the parchment, 1 inch apart. Sprinkle pistachios on 8 berries right away, while the coating still looks wet and shiny. Work in batches of 4 berries.

Chill the baking sheet for 15 to 20 minutes, until the shell looks matte, feels dry, and shows no fingerprint when touched lightly.

Microwave the white chocolate chips in the small bowl at 50% power for 20 seconds, then stir. Repeat 3 to 4 times, stopping the moment it stirs smooth and falls from the spoon in a smooth ribbon.

Spoon the white chocolate into the zip-top bag, snip a 1/8-inch corner, and drizzle zigzag lines over the berries. The lines should stay thin and hold their shape.

Chill 10 more minutes, until the drizzle looks matte and feels firm at the edges of each line. Serve right away or store.