1 pound small red potatoes
1 pound green beans
3 ears sweet corn (3 to 3 1/2 cups kernels)
1 medium yellow onion, sliced thinly
1/4 cup (1/2 stick) unsalted butter
2 tablespoons lemon juice, from 1 lemon
Black pepper, to taste
Scrub the potatoes clean and then cut them into bite-sized pieces. Place them in a medium-sized pot with 1 tablespoon of salt, and cover with cold water. Bring the water to a boil, then reduce to a simmer. Cook until the potatoes are tender and easily pierced with a fork, 3 to 5 minutes. Scoop the potatoes out with a slotted spoon and transfer to a mixing bowl.
While the potatoes are cooking, trim the green beans and cut them into bite-sized pieces. Once the potatoes have finished, bring the cooking water back to a boil (adding more water if necessary), and blanch the beans until they are bright green and tender, but still have some bite to them, 3 to 5 minutes. Remove with a slotted spoon and transfer to the bowl with the potatoes.
Cook the corn following your preferred method. Personally, I like using the microwave method for this recipe, because then I can multitask! Once the corn is cool enough to handle, cut off all the kernels and transfer them to the bowl with the potatoes and green beans.
When all the other vegetables are ready, cook the onions and make the brown butter dressing (or if you're confident in your multitasking skills, get the onions cooking on a separate burner while the other vegetables are cooking). Heat a teaspoon of oil in a skillet over medium heat, and cook the onions until they are soft and beginning to brown, 6 to 8 minutes. If you have the time and patience, continue slowly cooking the onions until they are fully caramelized — this is fantastic! Transfer the cooked onions into the bowl with the potatoes and beans.
Place the empty skillet back over medium-high heat and melt the butter. Continue cooking, occasionally swirling the butter in the pan, until the butter darkens and begins to smell nutty. Remove from heat and let the butter cool slightly, then whisk in the lemon juice and 1/2 teaspoon of salt. If the butter is still quite hot, the lemon juice will make it sizzle up and sputter — be careful!
Drizzle the lemon-brown butter sauce over the vegetables and toss to combine. Sprinkle with cheese, if using, and add salt and pepper to taste. This side dish can be served warm or room temperature. It will keep for 1 week refrigerated — the butter sauce will solidify in