To make whipped feta, add feta to a food processor with lemon juice, olive oil, and black pepper. Process until smooth, about a minute. Adjust until you have the right consistency. You might need more liquid depending on your feta.
Spread whipped feta out on a large platter. Top with cubed watermelon. (Seedless is best).
Top with slivered red onion and fresh basil.
Drizzle with good quality olive oil and flakey salt.