The following considerations are important in this scenario:

Include the Document Currency code cbc:DocumentCurrencyCode which must contain the code of the foreign currency, while the local Polish currency must be provided as Tax Currency code in cbc:TaxCurrencyCode.
Provide the Tax Identification Number of the Buyer cac:PartyTaxScheme/cbc:CompanyID
A second Tax Breakdown cac:TaxTotal group is required to provide the Tax Amount for each breakdown in the Tax Currency cbc:TaxCurrencyCode. In case the Total TaxAmount is zero no breakdown is required, but still can be provided.
On line level provide cac:TaxExemptionCode = VRBL:PL:EX and zero as Tax Rate cbc:Percent.

Example

<ubl:Invoice>
    <!-- code omitted for clarity -->
    <cbc:DocumentCurrencyCode>USD</cbc:DocumentCurrencyCode>
    <cbc:TaxCurrencyCode>PLN</cbc:TaxCurrencyCode>
    <!-- code omitted for clarity -->
    <cac:AccountingCustomerParty>
        <cac:Party>
            <cac:PartyTaxScheme>
                <cbc:CompanyID>DE999999999</cbc:CompanyID>
                <cac:TaxScheme>
                    <cbc:ID>VAT</cbc:ID>
                </cac:TaxScheme>
            </cac:PartyTaxScheme>
        </cac:Party>
    </cac:AccountingCustomerParty>
    <cac:TaxTotal>
        <!-- TaxTotal in Document Currency -->
        <cbc:TaxAmount currencyID="USD">3118.8</cbc:TaxAmount>
        <cac:TaxSubtotal>
            <cbc:TaxableAmount currencyID="USD">13560</cbc:TaxableAmount>
            <cbc:TaxAmount currencyID="USD">3118.8</cbc:TaxAmount>
            <cac:TaxCategory>
                <cbc:ID>VRBL:PL:06.03</cbc:ID>
                <cbc:Percent>23</cbc:Percent>
                <cac:TaxScheme>
                    <cbc:ID>VAT</cbc:ID>
                </cac:TaxScheme>
            </cac:TaxCategory>
        </cac:TaxSubtotal>
    </cac:TaxTotal>
    <cac:TaxTotal>
        <!-- TaxTotal in Tax Currency -->
        <cbc:TaxAmount currencyID="PLN">0</cbc:TaxAmount>
    </cac:TaxTotal>
    <!-- code omitted for clarity -->
    <cac:InvoiceLine>
        <!-- code omitted for clarity -->
        <cac:Item>
            <cbc:Name>lodówka Zimnotech mk1</cbc:Name>
            <cac:ClassifiedTaxCategory>
                <cbc:ID>VRBL:PL:06.03</cbc:ID>
                <cbc:Percent>0</cbc:Percent>
                <cbc:TaxExemptionReasonCode>VRBL:PL:EX</cbc:TaxExemptionReasonCode>
                <cac:TaxScheme>
                    <cbc:ID>VAT</cbc:ID>
                </cac:TaxScheme>
            </cac:ClassifiedTaxCategory>
        </cac:Item> 
        <!-- code omitted for clarity -->
        <cac:Price>
            <!-- Code omitted for clarity -->
            <cbc:PriceAmount currencyID="EUR">1000.00</cbc:PriceAmount>
        </cac:Price>
        <!-- code omitted for clarity -->
    </cac:InvoiceLine>
</ubl:Invoice>