Heat 2 tablespoons safflower oil in heavy 10-inch skillet over high heat. Add shrimp in batches and cook just until opaque about 45 seconds per side. Cool slightly. Peel and de-vein shrimp, leaving tails attached. Cool completely. (Can be prepared 1 day ahead.) Using steel knife: Mince green onions. Transfer to small bowl. Add dill. Cut bell pepper lengthwise into 4 pieces; discard core and ribs. Using thin slicer: Stand pepper pieces in feed tube, packing tightly. Slice using light pressure. Add to green onions. Stand cucumbers in feed tube and slice using medium pressure. transfer cucumbers to colander and toss with 1/4 teaspoon salt. Let stand 30 minutes. Rinse cucumbers and pat dry with towel. Add to bell pepper with vinegar, 3 tablespoons vegetable oil, tarragon, sugar, 1/4 teaspoon salt and pepper. (Can be prepared 1 day ahead and refrigerated.) Run knife between each tomato mousse and sides of molds. Carefully invert one into center of each plate. Smooth sides, using small knife. Surround each with cucumber-bell pepper salad. Arrange shrimp around outer edge. Garnish with basil and lemon wedges. Serve immediately.