In a large bowl, dissolve yeast in warm water. Add sugar, salt, eggs, oil and 3 cups flour; beat on medium speed until smooth. Stir in enough remaining flour to form a soft dough.
Turn dough onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Place in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1 hour.
Punch down dough. Divide in half and shape into loaves. Place in two greased 9×5-in. loaf pans. Cover with kitchen towels; let rise in a warm place until doubled, about 1 hour. Preheat oven to 375°.
Bake until golden brown, 25-30 minutes. Remove from pans to wire racks to cool.
Coarse-flake sea salt for sprinkling (preferably fleur de sel)
Preheat the oven to 325˚F. Line a cookie sheet with parchment paper.
In a saucepan over medium heat, melt the butter until it starts to brown. When the butter has browned and is ready, the foam will have subsided and it will have turned a nutty color. Watch closely so as not to burn the butter. Pour the browned butter into a medium bowl and stir in the brown sugar and vanilla. In a small bowl, whisk the flour and baking powder together. With a spoon, stir the flour mixture into the butter mixture until combined. Drop the dough by tablespoonfuls onto the cookie sheet. Sprinkle with sea salt and lightly press it into the top of cookies. Bake for 12 minutes.
Place raspberries in a food processor; cover and process until blended. Strain raspberries, reserving juice. Discard seeds. Place juice in a Dutch oven; stir in sugar and lemon juice. Heat over medium-high heat to 190°. Do not boil.
Remove from heat; skim off foam. Carefully ladle hot mixture into five hot 1-pint jars, leaving 1/4-in. headspace. Wipe rims; screw on bands until fingertip tight.
Place jars into canner simmering water, ensuring that they are completely covered with water. Bring to a boil; process for 10 minutes. Remove jars and cool.
To use concentrate: Mix 1 pint concentrate with 1 pint tonic water. Serve over ice.