Peel cucumbers. Reserve peel. Cut in half lengthwise. Remove and reserve seeds. Cut into 1/2in slices (approx 4 cups).

Cut tomatoes in half lengthwise. Remove and reserve seeds. Cut into 3/4in pieces (approx 5 cups).

Combine 1 1/2 cup tomatoes, lime juice, basil, garlic and 2 Tbsp vinegar in blender. Add reserved seeds and peel. Process until smooth, approx 30 seconds.

Line a fine strainer with double layer of cheese cloth and strain. Discard solids. Season dressing to taste.

Combine onion, 1/4tsp salt and remaining 2 Tbsp vinegar in bowl. Toss to coat. Add bell peppers, reserved cucumber slices, chopped tomatoes and 1 tsp salt. Toss to combine.

Stir in dressing. Let stand approx 20min, stirring occasionally. Drizzle with oil and season with salt.

Serving: use slotted spoon and garnish with basil.