Francisco de Zubrarán
Oil on canvas
The Hermitage, St. Petersburg, Russia
The saint holds the gridiron that was the instrument of his martyrdom. Lorite Cruz (184) suggests that his dalmatic is red because that is the liturgical color for the feast days of martyrs. That is, on those days the priest's outer vestment is a red chasuble and the deacon's a red dalmatic.
More of St. Lawrence
Source: Wikimedia Commons