To dip the morsel, or sop, whether it were bread or meat, in the dish containing the vinegar (compare Matthew 26:23; Mark 14:20 : Exodus 25:29; Numbers 7:13) was, and still is, the common custom in the East.
Parched or “roasted” corn - Grain was the common food of the country then (compare 1 Samuel 17:17; 1 Samuel 25:18; 2 Samuel 17:28) as it is now.
And left - Or “reserved” Ruth 2:18. Rather, “had some over” (compare Luke 15:17). Ruth 2:18 tells us that she took to her mother-in-law what she had left over.