Step 1In a large pot over medium heat, cook bacon, stirring occasionally, until crispy and fat has been rendered, 5 to 7 minutes. Using a slotted spoon, transfer bacon to a large bowl.
Step 2Reduce heat to low. Stir butter into bacon grease and cook until butter has melted. Add lobster and cook, stirring occasionally, until cooked through and firm, 4 to 6 minutes. Using slotted spoon, transfer lobster to bowl with bacon.
Step 3Add water to remaining grease and butter in saucepan and bring to a boil. Cook pasta according to package instructions.
Step 4Meanwhile, add celery, onion, tomatoes, mayonnaise, lemon juice, garlic, tarragon, salt, and black pepper to bowl with lobster mixture. Stir until thoroughly combined.
Step 5Drain pasta and let cool slightly. Add pasta to bowl and toss to combine.
Step 6Serve pasta salad warm, or cover bowl with plastic wrap and chill 2 hours before serving.
