Begin by rinsing the cucumbers, red onions, and bell peppers thoroughly under cold water. Slice the cucumbers and bell peppers into thin, uniform pieces, and slice the red onion thinly. Gather these vegetables in a large mixing bowl.

In a medium-sized bowl, combine the white vinegar, water, sugar, salt, black pepper, garlic powder, and dill (if using). Whisk together until the sugar and salt are fully dissolved.

Pour the pickling solution over the sliced cucumbers, onions, and bell peppers. Gently toss to coat the vegetables in the solution.

Cover the bowl with plastic wrap or transfer to an airtight container. Let it sit at room temperature for at least 10 minutes or refrigerate for several hours for more flavor.

Before serving, give the salad a gentle stir to redistribute the flavors. Serve cold or at room temperature.