Place red potatoes in large stockpot of water with 1-2 teaspoons of kosher salt. Bring potatoes to boil and reduce to bubbly simmer. Cook for about 7-8 minutes or until fork easily pierces potatoes.: You will hear a gentle rush as the water begins to warm, and the aroma of the salted water is subtle but foundational. Salting early seasons the potatoes from the inside out, so they taste layered rather than flat. The pot should have enough water to cover the potatoes by an inch, and using a pot that is too small can cause uneven cooking. A common mistake is using too little water, which makes the surface starch concentration uneven and can lead to gummy texture.
Add peas to potatoes and cook for 1 minute more or until they turn bright green. Carefully drain peas and potatoes without crushing peas.: As the water transitions from still to active, you will see rolling bubbles that then soften to a steady simmer. This gentle motion cooks the potatoes evenly without jostling them into pieces. Rapid, violent boiling can break delicate skins and cause water to evaporate too quickly, altering cook time. Watch the surface for consistent small bubbles rather than a furious boil, and adjust the heat to maintain that rhythm.
Melt butter in same pot and add potatoes and peas back to pot. Season with kosher salt and freshly ground black pepper. Sprinkle with dill, stir gently to combine and serve immediately.: You will notice a faint steam scent and a slight change in the potatoes’ color as they approach doneness. Use a fork to test near the center of a larger potato; it should slide in with light resistance. This test prevents overcooking, which leads to collapsing flesh that will not hold up when tossed. Avoid the temptation to skip the fork check, because visual cues alone can be misleading depending on potato size.
Add peas to potatoes and cook for 1 minute more or until they turn bright green: The peas will hiss and bob briefly as they hit the hot water, and their color will snap to a vivid green almost immediately. This short burst of heat is enough to cook them through while preserving sweetness and texture. Overcooking here dulls the color and makes the peas mushy, so time it carefully and set a timer if you need to.
Carefully drain peas and potatoes without crushing peas: Drain in a colander and give it a gentle shake to remove excess water, but be mindful not to press the vegetables through the holes. You may feel a light steam release and smell concentrated vegetable sweetness. Letting the produce sit in hot water too long after draining can continue cooking, so move quickly to the next step. A common error is shaking too vigorously, which can bruise the peas and break the potatoes.
Melt butter in same pot and add potatoes and peas back to pot: The butter will sizzle softly and release a warm, creamy aroma as it melts. Returning the vegetables to the empty pot allows the butter to coat them evenly, creating a glossy finish that carries seasoning. The residual heat helps the butter to meld into the surfaces without overcooking. If the pot is too hot and the butter browns, you'll change the flavor, so keep the heat low to medium.
Season with kosher salt and freshly ground black pepper: Once the butter has coated the vegetables, sprinkle salt and grind pepper over them, then gently toss. You will notice the seasoning heighten the flavors immediately, bringing out the natural sweetness of the peas and the earthiness of the potatoes . Season incrementally and taste, because you can always add more but not take it away. A common mistake is over-salting; taste before adding large amounts.
Sprinkle with dill, stir gently to combine and serve immediately: The fragrance of the fresh dill is bright and slightly citrusy, and sprinkling it last preserves that lift. Gently turning the vegetables ensures even distribution without crushing them, and the finished dish should glisten and smell herbaceous. Serve right away while warm for best texture. If held too long, the dill will wilt and the butter may congeal, dulling the final presentation.