To cut down on prep time, use a mandoline or food processor to slice the fennel. Prepare the salad a couple of hours ahead to allow the flavors to meld. Add fresh lemon juice immediately before serving if you like a tangy dish.
Place tomato in a medium bowl; mash lightly with the back of a spoon. Add vinegar and next 5 ingredients (through garlic) to bowl; toss to combine. Add fennel and remaining ingredients; cover and chill.
Delicious! Slice the fennel and onion as thinly as possible.