Remove stems from kale. Tear leaves into 2-inch pieces; wash and thoroughly dry, then toss well with 4 teaspoons oil in large bowl. Spread roughly one-third of leaves in single layer on large plate and season lightly with kosher salt. Microwave for 3 minutes. If leaves are crispy, transfer to serving bowl; if not, continue to microwave leaves in 30-second increments until crispy. Repeat with remaining leaves in 2 batches. Store chips in airtight container for up to 1 week.