Cook pasta according to package directions, omitting salt and fat.
Drain in a colander over a bowl, reserving 2/3 cup cooking liquid.
Heat a large nonstick skillet over medium-high heat.
Add oil; swirl to coat.
Add onion; cook 9 minutes or until lightly browned, stirring occasionally. Stir in garlic; cook 2 minutes or until garlic is lightly browned, stirring occasionally. Stir in edamame and peas; cook 2 minutes or until thoroughly heated.
Add pasta, rind, juice, and butter; stir until butter melts.
Remove pan from heat; stir in pecorino Romano cheese, mint, salt, and pepper. Stir in reserved 2/3 cup cooking liquid.