chop: cut 2 eggplants into 1-inch diced pieces. mix with olive oil and salt: mix with 1/4 cup olive oil and 3/4 teaspoon salt. eggplant soaks up the oil in an instant, so mix it right as soon as the oil hits its flesh. roast at 425 degrees: roast for about 30 to 35 minutes until the eggplant is browned and tender.