Step 1

Place 2 lb. mixed heirloom tomatoes, cut into wedges, in a fine-mesh sieve set over a medium bowl (to catch tomato water); season liberally with kosher salt and toss to distribute. Let sit 20 minutes.

Step 2

Meanwhile, cook 1 cup (packed) basil leaves in a small saucepan of boiling salted water, stirring, 30 seconds. Drain and gently press to remove excess water.

Step 3

Transfer basil to a small food processor or blender, add 3 Tbsp. grapeseed or vegetable oil, and process until smooth. Pour basil oil through a fine-mesh sieve into a small bowl and press on solids to extract as much basil as possible; discard solids. Whisk in 1 Tbsp. unseasoned rice vinegar and 2 Tbsp. tomato water to combine.

Step 4

Transfer tomatoes to a medium bowl and drizzle half of dressing over; toss to combine. Transfer to a platter or shallow bowls, top with one 8-oz. ball burrata or fresh mozzarella, torn into large pieces, and drizzle with remaining dressing. Scatter more basil over; season with freshly ground black pepper.