Prep the peas - Destem and string the peas, as needed. Blanch them in boiling water for no longer than sixty seconds, and plunge them in ice water to arrest the cooking. Slice the pea pods. There's no wrong way to do it, but it's fun to see a cross section of peas and to have some of the peas roll out of their pods. It's all good.
Make the vinaigrette and marinate the red onions - Zest and squeeze the lemon. Whisk the oil and vinegar together. Then add the lemon zest, 2 T of the lemon juice, the sugar, and the salt and pepper, and whisk again to emulsify and dissolve the sugar. Thinly slice the red onion and add it to the vinaigrette. Let onions marinate in the vinaigrette for about 15 minutes.
Assemble the salad - add the peas to a medium bowl. Tear the mint leaves in to bite-sized pieces. Chop a handful of dill. Add the herbs to the bowl with the peas and toss. Pull the onions out of the vinaigrette with tongs and add to the bowl as well. Toss.
Finish the salad - Pour some of the vinaigrette over the salad and give it a good toss. Taste, and add the rest of the vinaigrette to the salad if it's to your liking. Crumble the goat cheese and scatter it over the salad, giving it another quick toss before serving.
Notes
Don't tear the mint leaves much in advance of assembling and serving this salad, as they tend to darken pretty quickly after they've been torn.