Using Santoku Knife, slice cucumbers crosswise into sixteen ½-in. (1-cm) slices. Lightly scoop out flesh to create shallow wells using scoop end of Core & More, leaving bottoms of cups intact. Set aside.
Cut tomatoes into quarters lengthwise using Chef’s Knife; core and remove seeds. Dice pepper and onion into 1-in. (2.5-cm) pieces.
Process pepper, onion and basil in Manual Food Processor. Add tomatoes and garlic pressed with Garlic Press; finely process.
Carefully remove blade from processor bowl. Stir oil, vinegar and salt into pepper mixture in processor bowl.
Using level Small Scoop, scoop filling into cucumber cups. Garnish with additional basil, if desired.