Google Sheets – How to Remove Blank Line When Using UNIQUE

My approach would be to "normalise" the data first:

=ArrayFormula(IF({1,0};IFERROR(REGEXEXTRACT(A2:A;"^([a-zA-Z]+)"));B2:B))

and then you can actually wrap this directly in a QUERY function to produce the desired output:

=ArrayFormula(QUERY(IF({1,0};IFERROR(REGEXEXTRACT(A2:A;"^([a-zA-Z]+)"));B2:B);"select Col1, sum(Col2) where Col1 != '' group by Col1 label sum(Col2) ''";0))

You can even output a header row as well:

=ArrayFormula(QUERY(IF({1,0};IFERROR(REGEXEXTRACT(A2:A;"^([a-zA-Z]+)"));B2:B);"select Col1, sum(Col2) where Col1 != '' group by Col1 label Col1 'Food Item', sum(Col2) 'Total'";0))

I would write a custom function for this, to be used as

=combinations(table1!B2:B, table1!C2:C, table2!A2:A, table2!C2:C)

that is, the parameters are ValueColumn1, KeyColumn1, ValueColumn2, KeyColumn2.

The logic is entirely straightforward: run a double loop and collect whatever matches.

function combinations(range1, key1, range2, key2) {
  var output = [];
  if (range1.length != key1.length || range2.length != key2.length) {
    throw new Error('Each range must have the same length as its key'); 
  }
  for (var i = 0; i < range1.length; i++) {
    for (var j = 0; j < range2.length; j++) {
      if (key1[i][0] === key2[j][0] && key1[i][0] !== '') {
        output.push([range1[i][0], range2[j][0]]);
      }
    }
  }
  return output;
}