Combine peas, cucumbers, and tomatoes in a large bowl. Sprinkle with the salt and pepper and refrigerate 20 minutes.
In a small bowl, whisk together the oil, vinegars, and garlic. Add the sugar and whisk to combine.
Pour everything over the veggies and sprinkle with dill and pepper flakes. Serve immediately or cover and serve within the hour. The cucumbers will start to pickle if you wait too long.
