Carefully pick over crab, removing any bits of shell. Place in a mixing bowl. 

Grate lemon, reserving one teaspoon grated rind. Squeeze juice; strain to remove seeds. Combine juice and garlic in a blender; pulse until garlic is finely chopped. Add sour cream and mayonnaise; pulse three or four times until blended. Add green onion tops and basil, salt, and pepper; pulse five or six times or until blended, stopping to scrape down sides with a spatula. Pour mixture over picked crab. Add cream cheese and reserved one teaspoon grated lemon rind; mix well. 

Remove any long stems from spinach; finely chop and add to dip mixture. Quarter each tomato; cut away and discard core and seeds. Chop tomato meat; add to dip mixture and mix well. Taste; adjust seasoning. Place in a one quart container, cover tightly with a lid or plastic wrap, and chill at least two hours or up to 5 days. Serve with crackers, fresh sliced bread and your favorite crudités.