Step 1

Thinly slice 1/2 small red onion into half-moons. Place in a small bowl and cover with cool water. Let sit for 5 minutes.

Step 2

Meanwhile, prepare the following, adding each to the same medium bowl as it is completed: Halve 1 pound medium tomatoes through the stem end and use a spoon to scoop out the seeds and core of the tomatoes. Cut the tomatoes into 1/4-inch thick wedges. Coarsely chop the leaves and tender stems of 1/2 medium bunch fresh cilantro (about 1/2 cup). Trim and mince 1 medium jalapeño (about 2 tablespoons, remove the seeds and membrane first for a less spicy heat if desired).

Step 3

Drain the onions and add to the bowl with the tomatoes. Halve 1 medium lemon and squeeze the juice from one half over the salad (about 2 tablespoons). Season with 1 teaspoon kosher salt and toss to combine. Drizzle with 2 tablespoons extra-virgin olive oil and let sit for 5 minutes. Taste and season with more lemon juice, olive oil, or salt as needed.