1. Grate zest from lemons to equal 2 tsp. Cut lemons in half; squeeze juice from lemons to equal 1/2 cup.
2. Prepare pasta according to package directions. Whisk together shallots, next 4 ingredients, and lemon juice. Toss together pasta and shallot mixture. Cover with plastic wrap, and chill 1 to 48 hours.
3. Toss together pasta, peas, snow peas, next 2 ingredients, and lemon zest just before serving. Add salt, pepper, and additional lemon juice to taste.